[modules, api] Restrict GetModuleNamespace to evaluated modules.

Allowing GetModuleNamespace on a not-yet-evaluated module does not make a
lot of sense because accessing the namespace object before evaluation
can lead to surprising behavior.

R=adamk@chromium.org

Bug: v8:1569
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I3e3feb344f6399bf92b3dabc97c571a61b38bd41
Reviewed-on: https://chromium-review.googlesource.com/613268Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47365}

include/v8.h

@@ -1170,8 +1170,8 @@ class V8_EXPORT Module {
   V8_WARN_UNUSED_RESULT MaybeLocal<Value> Evaluate(Local<Context> context);
 
   /**
-   * Returns the namespace object of this module. The module must have
-   * been successfully instantiated before and must not be errored.
+   * Returns the namespace object of this module.
+   * The module's status must be kEvaluated.
    */
   Local<Value> GetModuleNamespace();
 };

src/api.cc

@@ -2159,10 +2159,9 @@ Location Module::GetModuleRequestLocation(int i) const {
 
 Local<Value> Module::GetModuleNamespace() {
   Utils::ApiCheck(
-      GetStatus() != kErrored && GetStatus() >= kInstantiated,
-      "v8::Module::GetModuleNamespace",
-      "GetModuleNamespace should be used on a successfully instantiated"
-      "module. The current module has not been instantiated or has errored");
+      GetStatus() == kEvaluated, "v8::Module::GetModuleNamespace",
+      "v8::Module::GetModuleNamespace can only be used on a module with "
+      "status kEvaluated");
   i::Handle<i::Module> self = Utils::OpenHandle(this);
   i::Handle<i::JSModuleNamespace> module_namespace =
       i::Module::GetModuleNamespace(self);