feat(expression_transformer): Parse NgTemplateCache values

Parse html files from NgTemplateCache annotations for expressions, allowing developers the ease
of including files needed to be parsed without specifying them individually in the pubspec.yaml
definition.

Closes #1644

lib/tools/transformer/expression_generator.dart

@@ -84,8 +84,7 @@ class ExpressionGenerator extends Transformer with ResolverTransformer {
         .toList();
 
     // Get all of the contents of templates in @Component(templateUrl:'...')
-    gatherReferencedUris(transform, resolver, options,
-        templatesOnly: true).then((templates) {
+    gatherReferencedUris(transform, resolver, options).then((templates) {
       templates.values.forEach(controller.add);
     }).then((_) {
       // Add any HTML files referencing this Dart file.

test/tools/transformer/expression_generator_spec.dart

@@ -92,6 +92,33 @@ main() {
           symbols: []);
     });
 
+    it('should follow template cache uris', () {
+      return generates(phases,
+          inputs: {
+            'a|web/main.dart': '''
+                import 'package:angular/angular.dart';
+                import 'package:angular/cacheAnnotation.dart';
+
+                @NgTemplateCache(
+                    preCacheUrls: ['lib/foo.html', 'packages/b/bar.html'])
+                class FooClass {}
+
+                main() {}
+                ''',
+            'a|lib/foo.html': '''
+                <div>{{template.contents}}</div>''',
+            'b|lib/bar.html': '''
+                <div>{{bar}}</div>''',
+            'a|web/index.html': '''
+                <script src='main.dart' type='application/dart'></script>''',
+            'angular|lib/angular.dart': libAngular,
+            'angular|lib/cacheAnnotation.dart': libCacheAnnotation,
+          },
+          getters: ['template', 'contents', 'bar'],
+          setters: ['template', 'contents', 'bar'],
+          symbols: []);
+    });
+
     it('should generate expressions for variables found in superclass', () {
       return generates(phases,
       inputs: {
@@ -248,3 +275,11 @@ class NgAttr {
   const NgAttr(String attrName);
 }
 ''';
+
+const String libCacheAnnotation = '''
+library angular.template_cache_annotation;
+
+class NgTemplateCache {
+  const NgTemplateCache({List preCacheUrls, bool cache});
+}
+''';