Support compilation of Hello World

pkg/compiler/lib/src/js_backend/backend.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of js_backend;
 
 const VERBOSE_OPTIMIZER_HINTS = false;
 
 class JavaScriptItemCompilationContext extends ItemCompilationContext {
   final Set<HInstruction> boundsChecked = new Set<HInstruction>();
@@ skipping 1456 matching lines @@
     if (kind == ElementKind.TYPEDEF) {
       return const WorldImpact();
     }
     if (element.isConstructor &&
         element.enclosingClass == helpers.jsNullClass) {
       // Work around a problem compiling JSNull's constructor.
       return const CodegenImpact();
     }
     if (kind.category == ElementCategory.VARIABLE) {
       VariableElement variableElement = element;
-      ConstantValue initialValue =
-          constants.getConstantValue(variableElement.constant);
-      if (initialValue != null) {
+      ConstantExpression constant = variableElement.constant;
+      if (constant != null) {
+        ConstantValue initialValue = constants.getConstantValue(constant);
         registerCompileTimeConstant(initialValue, work.registry);
         addCompileTimeConstantForEmission(initialValue);
         // We don't need to generate code for static or top-level
         // variables. For instance variables, we may need to generate
         // the checked setter.
         if (Elements.isStaticOrTopLevel(element)) {
           return impactTransformer
               .transformCodegenImpact(work.registry.worldImpact);
         }
       } else {
@@ skipping 354 matching lines @@
 
   void onLibraryCreated(LibraryElement library) {
     helpers.onLibraryCreated(library);
   }
 
   Future onLibraryScanned(LibraryElement library, LibraryLoader loader) {
     return super.onLibraryScanned(library, loader).then((_) {
       if (library.isPlatformLibrary &&
           // Don't patch library currently disallowed.
           !library.isSynthesized &&
-          !library.isPatched) {
+          !library.isPatched &&
+          // Don't patch deserialized libraries.
+          !compiler.serialization.isDeserialized(library)) {
         // Apply patch, if any.
         Uri patchUri = compiler.resolvePatchUri(library.canonicalUri.path);
         if (patchUri != null) {
           return compiler.patchParser.patchLibrary(loader, patchUri, library);
         }
       }
     }).then((_) {
       helpers.onLibraryScanned(library);
       Uri uri = library.canonicalUri;
       if (uri == Uris.dart_html) {
@@ skipping 1154 matching lines @@
 
   @override
   void onImpactUsed(ImpactUseCase impactUse) {
     if (impactUse == DeferredLoadTask.IMPACT_USE && !supportSerialization) {
       // TODO(johnniwinther): Allow emptying when serialization has been
       // performed.
       resolution.emptyCache();
     }
   }
 }