Implement rudimentary module linking.

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index 68d8c8401f9bc5526b45db5651e411995329e8aa..fc7a1a429db1f63bd33bcf79c7044cae60f73a49 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -1292,7 +1292,7 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_DeclareGlobals) {
     bool is_var = value->IsUndefined();
     bool is_const = value->IsTheHole();
     bool is_function = value->IsSharedFunctionInfo();
-    bool is_module = value->IsJSObject();
+    bool is_module = value->IsJSModule();
     ASSERT(is_var + is_const + is_function + is_module == 1);
 
     if (is_var || is_const) {
@@ -8609,6 +8609,25 @@ RUNTIME_FUNCTION(MaybeObject*, Runtime_PushBlockContext) {
 }
 
 
+RUNTIME_FUNCTION(MaybeObject*, Runtime_PushModuleContext) {
+  NoHandleAllocation ha;
+  ASSERT(args.length() == 2);
+  CONVERT_ARG_CHECKED(ScopeInfo, scope_info, 0);
+  CONVERT_ARG_HANDLE_CHECKED(JSModule, instance, 1);
+
+  Context* context;
+  MaybeObject* maybe_context =
+      isolate->heap()->AllocateModuleContext(isolate->context(),
+                                             scope_info);
+  if (!maybe_context->To(&context)) return maybe_context;
+  // Also initialize the context slot of the instance object.
+  instance->set_context(context);
+  isolate->set_context(context);
+
+  return context;
+}
+
+
 RUNTIME_FUNCTION(MaybeObject*, Runtime_DeleteContextSlot) {
   HandleScope scope(isolate);
   ASSERT(args.length() == 2);