dart2js: add compiler builtins to the core-runtime.

pkg/compiler/lib/src/native/enqueue.dart

Index: pkg/compiler/lib/src/native/enqueue.dart
diff --git a/pkg/compiler/lib/src/native/enqueue.dart b/pkg/compiler/lib/src/native/enqueue.dart
index a7c7af93565c8b2a6a2d561e566748be15049e51..7d698b65f489d168b40cfe942e79d3d48d5b20aa 100644
--- a/pkg/compiler/lib/src/native/enqueue.dart
+++ b/pkg/compiler/lib/src/native/enqueue.dart
@@ -54,6 +54,18 @@ class NativeEnqueuer {
   // TODO(sra): The entry from codegen will not have a resolver.
   void registerJsEmbeddedGlobalCall(Send node, ResolverVisitor resolver) {}
 
+  /**
+   * Handles JS-compiler builtin calls, which can be an instantiation point for
+   * types.
+   *
+   * For example, the following code instantiates and returns a String class
+   *
+   *     JS_BUILTIN('String', 'int2string', 0)
+   *
+   */
+  // TODO(sra): The entry from codegen will not have a resolver.
+  void registerJsBuiltinCall(Send node, ResolverVisitor resolver) {}
+
   /// Emits a summary information using the [log] function.
   void logSummary(log(message)) {}
 
@@ -492,6 +504,14 @@ abstract class NativeEnqueuerBase implements NativeEnqueuer {
     flushQueue();
   }
 
+  void registerJsBuiltinCall(Send node, ResolverVisitor resolver) {
+    NativeBehavior behavior =
+        NativeBehavior.ofJsBuiltinCall(node, compiler, resolver);
+    processNativeBehavior(behavior, node);
+    nativeBehaviors[node] = behavior;
+    flushQueue();
+  }
+
   NativeBehavior getNativeBehaviorOf(Send node) => nativeBehaviors[node];
 
   processNativeBehavior(NativeBehavior behavior, cause) {