[modules] Implement namespace imports.

src/runtime/runtime-object.cc

Index: src/runtime/runtime-object.cc
diff --git a/src/runtime/runtime-object.cc b/src/runtime/runtime-object.cc
index 70ed23ba6190ba6b58cd234982156ac0f47e1ad5..fbaf9f305011412d53da7c8960cebae65ae3c031 100644
--- a/src/runtime/runtime-object.cc
+++ b/src/runtime/runtime-object.cc
@@ -960,6 +960,14 @@ RUNTIME_FUNCTION(Runtime_CreateDataProperty) {
   return *value;
 }
 
+RUNTIME_FUNCTION(Runtime_GetModuleNamespace) {

[adamk, 2016/10/04 18:26:53]

It occurs to me that maybe these runtime functions should be in a new
runtime-modules.cc file (no need to make that change in this CL).

[neis, 2016/10/05 08:18:41]

Yeah I was planning to do that eventually.

+  HandleScope scope(isolate);
+  DCHECK(args.length() == 1);
+  CONVERT_ARG_HANDLE_CHECKED(Smi, module_request, 0);

[adamk, 2016/10/04 18:26:53]

You can use CONVERT_SMI_ARG_CHECKED here to get an int directly.

[neis, 2016/10/05 08:18:42]

Done.

+  Handle<Module> module(isolate->context()->module());

[adamk, 2016/10/04 18:26:53]

Seems a little scary to depend on the current context; do you see us doing this
elsewhere in runtime code?

Still really confusing to me that module() walks the context chain...I guess
I'll send you a CL to change its name everywhere.

Is there any DCHECK we can put here to double-check that this runtime function
was called in the right context?

[neis, 2016/10/05 08:18:42]

I don't understand.  All the module runtime functions do this.

[adamk, 2016/10/05 17:21:54]

Sorry, you're right. Like I said, I need to rename that function so I understand
it better :)

+  return *Module::GetModuleNamespace(module, module_request->value());
+}
+
 RUNTIME_FUNCTION(Runtime_LoadModuleExport) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);