Support compilation of Hello World

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

Index: pkg/compiler/lib/src/js_backend/backend.dart
diff --git a/pkg/compiler/lib/src/js_backend/backend.dart b/pkg/compiler/lib/src/js_backend/backend.dart
index 83cab66a099824606efa90f4d95bd27a753a0693..143aad6f0f67582e684051f428190de2e3bebc9f 100644
--- a/pkg/compiler/lib/src/js_backend/backend.dart
+++ b/pkg/compiler/lib/src/js_backend/backend.dart
@@ -1474,9 +1474,9 @@ class JavaScriptBackend extends Backend {
     }
     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
@@ -1851,7 +1851,9 @@ class JavaScriptBackend extends Backend {
       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) {