[DevTools] Make resource tree model optional

third_party/WebKit/Source/devtools/front_end/components/ExecutionContextSelector.js

Index: third_party/WebKit/Source/devtools/front_end/components/ExecutionContextSelector.js
diff --git a/third_party/WebKit/Source/devtools/front_end/components/ExecutionContextSelector.js b/third_party/WebKit/Source/devtools/front_end/components/ExecutionContextSelector.js
index 442321322d2a0efb5c1c9d7d100a069045bed320..3ac34873f1e11a6c75bc97cfed773e1a59a778e9 100644
--- a/third_party/WebKit/Source/devtools/front_end/components/ExecutionContextSelector.js
+++ b/third_party/WebKit/Source/devtools/front_end/components/ExecutionContextSelector.js
@@ -132,9 +132,12 @@ WebInspector.ExecutionContextSelector.prototype = {
      */
     _isMainFrameContext: function(executionContext)

[pfeldman, 2016/07/07 17:44:14]

The name is misleading - we want to know whether this is a default context,
should be

_isDefault() and should check for belonging to the main target.

[eostroukhov-old, 2016/07/13 23:30:58]

Done. Note that the main target check is by checking if there's a parent target.
It is to make sure tests work - discussed it with +dgozman, 

     {
-        if (!executionContext.isDefault)
+        if (!executionContext.isDefault || !executionContext.frameId)
             return false;
-        var frame = executionContext.target().resourceTreeModel.frameForId(executionContext.frameId);
+        var resourceTreeModel = WebInspector.ResourceTreeModel.fromTarget(executionContext.target());
+        if (!resourceTreeModel)
+            return false;
+        var frame = resourceTreeModel.frameForId(executionContext.frameId);
         if (frame && frame.isMainFrame())
             return true;
         return false;