Remove the ENABLE_SCRIPTING build-target, since it's not necessary

There's no really compelling reason, as far as I can tell, to introduce the `ENABLE_SCRIPTING` build-target, instead of simply re-using the existing `TESTING` build-target for the new `gulp integrationtest` task.

In general there should be no problem with just always enable scripting in TESTING-builds, and if I were to *guess* the reason that this didn't seem to work was most likely because the Preferences ended up over-writing the `AppOptions`.
As it turns out the GENERIC-viewer has already has built-in support for disabling of Preferences, via the `AppOptions`, and this can be utilized in TESTING-builds as well to ensure that whatever `AppOptions` are set they're always respected.

gulpfile.js

@@ -97,7 +97,6 @@ const DEFINES = Object.freeze({
   PRODUCTION: true,
   SKIP_BABEL: true,
   TESTING: false,
-  ENABLE_SCRIPTING: false,
   // The main build targets:
   GENERIC: false,
   MOZCENTRAL: false,
@@ -661,7 +660,6 @@ gulp.task("default_preferences-pre", function () {
       LIB: true,
       BUNDLE_VERSION: 0, // Dummy version
       BUNDLE_BUILD: 0, // Dummy build
-      ENABLE_SCRIPTING: process.env.ENABLE_SCRIPTING === "true",
     }),
     map: {
       "pdfjs-lib": "../pdf",
@@ -1527,46 +1525,29 @@ gulp.task("testing-pre", function (done) {
   done();
 });
 
-gulp.task("enable-scripting", function (done) {
-  process.env.ENABLE_SCRIPTING = "true";
-  done();
-});
-
 gulp.task(
   "test",
-  gulp.series(
-    "enable-scripting",
-    "testing-pre",
-    "generic",
-    "components",
-    function () {
-      return streamqueue(
-        { objectMode: true },
-        createTestSource("unit"),
-        createTestSource("browser"),
-        createTestSource("integration")
-      );
-    }
-  )
+  gulp.series("testing-pre", "generic", "components", function () {
+    return streamqueue(
+      { objectMode: true },
+      createTestSource("unit"),
+      createTestSource("browser"),
+      createTestSource("integration")
+    );
+  })
 );
 
 gulp.task(
   "bottest",
-  gulp.series(
-    "enable-scripting",
-    "testing-pre",
-    "generic",
-    "components",
-    function () {
-      return streamqueue(
-        { objectMode: true },
-        createTestSource("unit", true),
-        createTestSource("font", true),
-        createTestSource("browser (no reftest)", true),
-        createTestSource("integration")
-      );
-    }
-  )
+  gulp.series("testing-pre", "generic", "components", function () {
+    return streamqueue(
+      { objectMode: true },
+      createTestSource("unit", true),
+      createTestSource("font", true),
+      createTestSource("browser (no reftest)", true),
+      createTestSource("integration")
+    );
+  })
 );
 
 gulp.task(
@@ -1585,7 +1566,7 @@ gulp.task(
 
 gulp.task(
   "integrationtest",
-  gulp.series("enable-scripting", "testing-pre", "generic", function () {
+  gulp.series("testing-pre", "generic", function () {
     return createTestSource("integration");
   })
 );

src/pdf.sandbox.js

@@ -48,8 +48,6 @@ class Sandbox {
     let code = [
       "exports = Object.create(null);",
       "module = Object.create(null);",
-      // Next line is replaced by code from initialization.js
-      // when we create the bundle for the sandbox.
       PDFJSDev.eval("PDF_SCRIPTING_JS_SOURCE"),
       `data = ${sandboxData};`,
       `module.exports.initSandbox({ data, extra: {${extraStr}}, out: this});`,

web/app_options.js

@@ -67,7 +67,7 @@ const defaultOptions = {
   },
   enableScripting: {
     /** @type {boolean} */
-    value: typeof PDFJSDev !== "undefined" && PDFJSDev.test("ENABLE_SCRIPTING"),
+    value: typeof PDFJSDev !== "undefined" && PDFJSDev.test("TESTING"),
     kind: OptionKind.VIEWER + OptionKind.PREFERENCE,
   },
   enableWebGL: {
@@ -249,7 +249,7 @@ if (
 ) {
   defaultOptions.disablePreferences = {
     /** @type {boolean} */
-    value: false,
+    value: typeof PDFJSDev !== "undefined" && PDFJSDev.test("TESTING"),
     kind: OptionKind.VIEWER,
   };
   defaultOptions.locale = {
@@ -260,8 +260,7 @@ if (
   defaultOptions.sandboxBundleSrc = {
     /** @type {string} */
     value:
-      typeof PDFJSDev === "undefined" ||
-      PDFJSDev.test("!PRODUCTION && !ENABLE_SCRIPTING")
+      typeof PDFJSDev === "undefined" || !PDFJSDev.test("PRODUCTION")
         ? "../build/dev-sandbox/pdf.sandbox.js"
         : "../build/pdf.sandbox.js",
     kind: OptionKind.VIEWER,