diff --git a/core/blockly.js b/core/blockly.js
index 1c7b37377b3..48fc78e21dc 100644
--- a/core/blockly.js
+++ b/core/blockly.js
@@ -184,6 +184,11 @@ goog.require('Blockly.Events.VarCreate');
  */
 exports.VERSION = 'uncompiled';
 
+/**
+ * @define {boolean} Overridden to true by the compiler.
+ */
+const COMPILED = false;
+
 // Add a getter and setter pair for Blockly.alert, Blockly.confirm,
 // Blockly.mainWorkspace, Blockly.prompt and Blockly.selected for backwards
 // compatibility.
@@ -700,7 +705,7 @@ exports.zelos = zelos;
 //
 // This is only needed in uncompiled mode (see
 // google/blockly-samples#902); in compiled mode the exports object is
-// already the value of globalThis.Blockly.
+// already the value of globalThis['Blockly'].
 //
 // Note that this code will still attempt to redefine accessors on a
 // previously-imported copy of the Blockly library if both are
@@ -708,8 +713,8 @@ exports.zelos = zelos;
 // accessors are nonconfigurable (which is good, as otherwise one
 // accessors on one copy would call get/set functions on the other
 // copy!)
-if (!goog.global['COMPILED'] && typeof goog.global['Blockly'] === 'object' &&
-    goog.global['Blockly'] !== exports) {
+if (!COMPILED && typeof globalThis['Blockly'] === 'object' &&
+    globalThis['Blockly'] !== exports) {
   const descriptors = Object.getOwnPropertyDescriptors(exports);
   const accessors = {};
   for (const key in descriptors) {
@@ -717,5 +722,5 @@ if (!goog.global['COMPILED'] && typeof goog.global['Blockly'] === 'object' &&
       accessors[key] = descriptors[key];
     }
   }
-  Object.defineProperties(globalThis.Blockly, accessors);
+  Object.defineProperties(globalThis['Blockly'], accessors);
 }
diff --git a/core/utils/xml.js b/core/utils/xml.js
index f11117a2e1a..10e675f8c3c 100644
--- a/core/utils/xml.js
+++ b/core/utils/xml.js
@@ -36,7 +36,7 @@ exports.NAME_SPACE = NAME_SPACE;
  * jsdom package instead.
  * @type {!Document}
  */
-let xmlDocument = globalThis.document;
+let xmlDocument = globalThis['document'];
 
 /**
  * Get the document object to use for XML serialization.
diff --git a/externs/block-externs.js b/externs/block-externs.js
deleted file mode 100644
index 20b6f51b1d3..00000000000
--- a/externs/block-externs.js
+++ /dev/null
@@ -1,28 +0,0 @@
-/**
- * @license
- * Copyright 2020 Google LLC
- * SPDX-License-Identifier: Apache-2.0
- */
-
-/**
- * @fileoverview Externs for Blockly blocks.
- * @externs
- */
-
-goog.provide('Blockly');
-goog.provide('Blockly.Blocks');
-goog.provide('Blockly.Comment');
-goog.provide('Blockly.FieldCheckbox');
-goog.provide('Blockly.FieldColour');
-goog.provide('Blockly.FieldDropdown');
-goog.provide('Blockly.FieldImage');
-goog.provide('Blockly.FieldLabel');
-goog.provide('Blockly.FieldMultilineInput');
-goog.provide('Blockly.FieldNumber');
-goog.provide('Blockly.FieldTextInput');
-goog.provide('Blockly.FieldVariable');
-goog.provide('Blockly.Mutator');
-goog.provide('Blockly.Warning');
-goog.provide('Blockly.loopMixin');
-
-var Blockly;
diff --git a/externs/generator-externs.js b/externs/generator-externs.js
deleted file mode 100644
index 6b6d9d650a7..00000000000
--- a/externs/generator-externs.js
+++ /dev/null
@@ -1,20 +0,0 @@
-/**
- * @license
- * Copyright 2020 Google LLC
- * SPDX-License-Identifier: Apache-2.0
- */
-
-/**
- * @fileoverview Externs for Blockly generators.
- * @externs
- */
-
-goog.provide('Blockly');
-goog.provide('Blockly.Generator');
-goog.provide('Blockly.inputTypes');
-goog.provide('Blockly.loopMixin');
-goog.provide('Blockly.utils.global');
-goog.provide('Blockly.utils.object');
-goog.provide('Blockly.utils.string');
-
-var Blockly;
diff --git a/externs/goog-externs.js b/externs/goog-externs.js
deleted file mode 100644
index dcc80965ae6..00000000000
--- a/externs/goog-externs.js
+++ /dev/null
@@ -1,66 +0,0 @@
-/**
- * @license
- * Copyright 2019 Google LLC
- * SPDX-License-Identifier: Apache-2.0
- */
-
-/**
- * @fileoverview Externs for goog.*
- *
- * These are needed because we use goog.module, goog.require etc. to
- * define our modules, but we don't actually include
- * closure/goog/base.js as input to the compiler.  Originally we only
- * needed the extern for goog, but some time between Closure Compiler
- * versions 20210601.0.0 and 20211006.0.0 we started getting
- * JSC_POSSIBLE_INEXISTENT_PROPERTY errors for goog.module /
- * goog.require / goog.requireType declarations involving modules
- * which used goog.module.declareLegacyNamespace.
- *
- * @externs
- */
-
-/**
- * @type {!Object}
- */
-var goog = {};
-
-/**
- * @param {string} name
- * @return {void}
- */
-goog.module = function(name) {};
-
-/**
- * @return{void}
- */
-goog.module.declareLegacyNamespace = function() {};
-
-/**
- * @param {string} name
- * @return {?}
- */
-goog.module.get = function(name) {};
-
-/**
- * @param {string} name
- * @return {void}
- */
-goog.provide = function(name) {};
-
-/**
- * @param {string} namespace
- * @return {?}
- */
-goog.require = function(namespace) {};
-
-/**
- * @param {string} namespace
- * @return {?}
- */
-goog.requireType = function(namespace) {};
-
-/**
- * @param {string=} opt_message
- * @return{void}
- */
-goog.setTestOnly = function(opt_message) {};
diff --git a/scripts/gulpfiles/build_tasks.js b/scripts/gulpfiles/build_tasks.js
index 4b34099caf2..529b6200f6e 100644
--- a/scripts/gulpfiles/build_tasks.js
+++ b/scripts/gulpfiles/build_tasks.js
@@ -183,56 +183,6 @@ var JSCOMP_ERROR = [
   'visibility'
 ];
 
-/**
- * Helper method for calling the Closure compiler.
- * @param {*} compilerOptions
- * @param {boolean=} opt_verbose Optional option for verbose logging
- * @param {boolean=} opt_warnings_as_error Optional option for treating warnings
- *     as errors.
- * @param {boolean=} opt_strict_typechecker Optional option for enabling strict
- *     type checking.
- */
-function compile(compilerOptions, opt_verbose, opt_warnings_as_error,
-    opt_strict_typechecker) {
-  const options = {};
-  options.compilation_level = 'SIMPLE_OPTIMIZATIONS';
-  options.warning_level = opt_verbose ? 'VERBOSE' : 'DEFAULT';
-  options.language_in = 'ECMASCRIPT6_STRICT',
-  options.language_out = 'ECMASCRIPT5_STRICT';
-  options.rewrite_polyfills = true;
-  options.hide_warnings_for = 'node_modules';
-  if (opt_warnings_as_error || opt_strict_typechecker) {
-    options.jscomp_error = JSCOMP_ERROR;
-    if (opt_strict_typechecker) {
-      options.jscomp_error.push('strictCheckTypes');
-    }
-  }
-
-  const platform = ['native', 'java', 'javascript'];
-
-  return closureCompiler({...options, ...compilerOptions}, { platform });
-}
-
-/**
- * Helper method for possibly adding the Closure library into a sources array.
- * @param {Array<string>} srcs
- */
-function maybeAddClosureLibrary(srcs) {
-  if (argv.closureLibrary) {
-    // If you require Google's Closure library, you can include it in your
-    // build by adding the --closure-library flag.
-    // You will also need to include the "google-closure-library" in your list
-    // of devDependencies.
-    console.log('Including the google-closure-library in your build.');
-    if (!fs.existsSync('./node_modules/google-closure-library')) {
-      throw Error('You must add the google-closure-library to your ' +
-        'devDependencies in package.json, and run `npm install`.');
-    }
-    srcs.push('./node_modules/google-closure-library/closure/goog/**/**/*.js');
-  }
-  return srcs;
-}
-
 /**
  * This task updates tests/deps.js, used by blockly_uncompressed.js
  * when loading Blockly in uncompiled mode.
@@ -493,6 +443,34 @@ function unflattenCorePaths(pathString) {
   return pathString.replace(/-slash-/g, path.sep);
 }
 
+/**
+ * Helper method for calling the Closure compiler, establishing
+ * default options (that can be overridden by the caller).
+ * @param {*} options Caller-supplied options that will override the
+ *     defaultOptions.
+ */
+function compile(options) {
+  const defaultOptions = {
+    compilation_level: 'SIMPLE_OPTIMIZATIONS',
+    warning_level: argv.verbose ? 'VERBOSE' : 'DEFAULT',
+    language_in: 'ECMASCRIPT6_STRICT',
+    language_out: 'ECMASCRIPT5_STRICT',
+    rewrite_polyfills: true,
+    hide_warnings_for: 'node_modules',
+    externs: ['./externs/svg-externs.js'],
+  };
+  if (argv.debug || argv.strict) {
+    defaultOptions.jscomp_error = [...JSCOMP_ERROR];
+    if (argv.strict) {
+      defaultOptions.jscomp_error.push('strictCheckTypes');
+    }
+  }
+  // Extra options for Closure Compiler gulp plugin.
+  const platform = ['native', 'java', 'javascript'];
+
+  return closureCompiler({...defaultOptions, ...options}, {platform});
+}
+
 /**
  * This task compiles the core library, blocks and generators, creating 
  * blockly_compressed.js, blocks_compressed.js, etc.
@@ -505,13 +483,6 @@ function buildCompiled() {
   // Closure Compiler options.
   const packageJson = getPackageJson();  // For version number.
   const options = {
-    compilation_level: 'SIMPLE_OPTIMIZATIONS',
-    warning_level: argv.verbose ? 'VERBOSE' : 'DEFAULT',
-    language_in: 'ECMASCRIPT6_STRICT',
-    language_out: 'ECMASCRIPT5_STRICT',
-    rewrite_polyfills: true,
-    hide_warnings_for: 'node_modules',
-    externs: ['./externs/svg-externs.js'],
     define: 'Blockly.VERSION="' + packageJson.version + '"',
     chunk: chunkOptions.chunk,
     chunk_wrapper: chunkOptions.chunk_wrapper,
@@ -519,21 +490,13 @@ function buildCompiled() {
     // Don't supply the list of source files in chunkOptions.js as an
     // option to Closure Compiler; instead feed them as input via gulp.src.
   };
-  if (argv.debug || argv.strict) {
-    options.jscomp_error = [...JSCOMP_ERROR];
-    if (argv.strict) {
-      options.jscomp_error.push('strictCheckTypes');
-    }
-  }
-  // Extra options for Closure Compiler gulp plugin.
-  const pluginOptions = ['native', 'java', 'javascript'];
 
   // Fire up compilation pipline.
   return gulp.src(chunkOptions.js, {base: './'})
       .pipe(stripApacheLicense())
       .pipe(gulp.sourcemaps.init())
       .pipe(gulp.rename(flattenCorePaths))
-      .pipe(closureCompiler(options, pluginOptions))
+      .pipe(compile(options))
       .pipe(gulp.rename({suffix: COMPILED_SUFFIX}))
       .pipe(gulp.sourcemaps.mapSources(unflattenCorePaths))
       .pipe(
@@ -547,38 +510,24 @@ function buildCompiled() {
  */
 function buildAdvancedCompilationTest() {
   const srcs = [
-    'tests/compile/main.js', 'tests/compile/test_blocks.js', 'core/**/**/*.js',
-    'blocks/*.js', 'generators/**/*.js'
+    'closure/goog/base_minimal.js',
+    'core/**/*.js', 'blocks/**/*.js', 'generators/**/*.js',
+    'tests/compile/main.js', 'tests/compile/test_blocks.js',
   ];
-  return gulp.src(maybeAddClosureLibrary(srcs), {base: './'})
+
+  // Closure Compiler options.
+  const options = {
+    dependency_mode: 'PRUNE',
+    compilation_level: 'ADVANCED_OPTIMIZATIONS',
+    entry_point: './tests/compile/main.js',
+    js_output_file: 'main_compressed.js',
+  };
+  return gulp.src(srcs, {base: './'})
       .pipe(stripApacheLicense())
       .pipe(gulp.sourcemaps.init())
-      // Directories in Blockly are used to group similar files together
-      // but are not used to limit access with @package, instead the
-      // method means something is internal to Blockly and not a public
-      // API.
-      // Flatten all files so they're in the same directory, but ensure that
-      // files with the same name don't conflict.
-      .pipe(gulp.rename(function(p) {
-        if (p.dirname.indexOf('core') === 0) {
-          var dirname = p.dirname.replace(
-              new RegExp(path.sep.replace(/\\/, '\\\\'), "g"), "-");
-          p.dirname = "";
-          p.basename = dirname + "-" + p.basename;
-        }
-      }))
-      .pipe(compile(
-          {
-            dependency_mode: 'PRUNE',
-            compilation_level: 'ADVANCED_OPTIMIZATIONS',
-            entry_point: './tests/compile/main.js',
-            js_output_file: 'main_compressed.js',
-            externs: ['./externs/svg-externs.js', './externs/goog-externs.js'],
-          },
-          argv.verbose, argv.strict))
-      .pipe(gulp.sourcemaps.mapSources(function(sourcePath, file) {
-        return sourcePath.replace(/-/g, '/');
-      }))
+      .pipe(gulp.rename(flattenCorePaths))
+      .pipe(compile(options))
+      .pipe(gulp.sourcemaps.mapSources(unflattenCorePaths))
       .pipe(gulp.sourcemaps.write(
           '.', {includeContent: false, sourceRoot: '../../'}))
       .pipe(gulp.dest('./tests/compile/'));
diff --git a/tests/compile/index.html b/tests/compile/index.html
index 8ffadca8893..97fb520316f 100644
--- a/tests/compile/index.html
+++ b/tests/compile/index.html
@@ -22,9 +22,8 @@
 <body>
   <h1>Blockly: Advanced Compilation Test</h1>
 
-  <p>To run this test manually, download
-  <a href="https://dl.google.com/closure-compiler/compiler-latest.zip">closure-compiler-vxxxxxxxx.jar</a>,
-  place it in this directory, then run `npm run test:compile:advanced` from the command line.</p>
+  <p>To run this test manually, run `npm run test:compile:advanced`
+  from the command line, then open this file in your web browser.</p>
 
   <p>Measure the size of main_compressed.js (295kb as of October 2017), then reload
   this page and see if Blockly works.</p>