Issue #618 - Remove eager instantiation

This backs out the stuff added in Bug 1295978.
Ref: BZ 1295978, 1388728

dom/script/ModuleScript.cpp

@@ -34,7 +34,6 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
 NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(ModuleScript)
   NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mModuleRecord)
-  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mException)
 NS_IMPL_CYCLE_COLLECTION_TRACE_END
 
 NS_IMPL_CYCLE_COLLECTING_ADDREF(ModuleScript)
@@ -44,13 +43,11 @@ ModuleScript::ModuleScript(ScriptLoader *aLoader, nsIURI* aBaseURL,
                            JS::Handle<JSObject*> aModuleRecord)
  : mLoader(aLoader),
    mBaseURL(aBaseURL),
-   mModuleRecord(aModuleRecord),
-   mInstantiationState(Uninstantiated)
+   mModuleRecord(aModuleRecord)
 {
   MOZ_ASSERT(mLoader);
   MOZ_ASSERT(mBaseURL);
   MOZ_ASSERT(mModuleRecord);
-  MOZ_ASSERT(mException.isUndefined());
 
   // Make module's host defined field point to this module script object.
   // This is cleared in the UnlinkModuleRecord().
@@ -68,7 +65,6 @@ ModuleScript::UnlinkModuleRecord()
     JS::SetModuleHostDefinedField(mModuleRecord, JS::UndefinedValue());
   }
   mModuleRecord = nullptr;
-  mException.setUndefined();
 }
 
 ModuleScript::~ModuleScript()
@@ -80,21 +76,5 @@ ModuleScript::~ModuleScript()
   DropJSObjects(this);
 }
 
-void
-ModuleScript::SetInstantiationResult(JS::Handle<JS::Value> aMaybeException)
-{
-  MOZ_ASSERT(mInstantiationState == Uninstantiated);
-  MOZ_ASSERT(mModuleRecord);
-  MOZ_ASSERT(mException.isUndefined());
-
-  if (aMaybeException.isUndefined()) {
-    mInstantiationState = Instantiated;
-  } else {
-    mModuleRecord = nullptr;
-    mException = aMaybeException;
-    mInstantiationState = Errored;
-  }
-}
-
 } // dom namespace
 } // mozilla namespace