Support merged Dart-JS callstacks

Source/core/inspector/InjectedScriptSource.js

Index: Source/core/inspector/InjectedScriptSource.js
diff --git a/Source/core/inspector/InjectedScriptSource.js b/Source/core/inspector/InjectedScriptSource.js
index 8c5cc460f4a6b4b56a89be75c385c0c793bfaffa..1018e458e143cc39de15d1e1e872aeac3d8370f0 100644
--- a/Source/core/inspector/InjectedScriptSource.js
+++ b/Source/core/inspector/InjectedScriptSource.js
@@ -976,7 +976,13 @@ InjectedScript.prototype = {
     _callFrameForParsedId: function(topCallFrame, parsedCallFrameId, asyncCallStacks)
     {
         var asyncOrdinal = parsedCallFrameId["asyncOrdinal"]; // 1-based index
-        if (asyncOrdinal)
+        // FIXMEDART: change this next line back to
+        // if (asyncOrdinal)
+        // once we can remove the hack of giving JavaScript callframes from
+        // mixed Dart-JavaScript call stacks ordinal -1 to trigger the
+        // safer code path used to simulate evaluating code on the call frame
+        // for async call frames.
+        if (asyncOrdinal >= 1)
             topCallFrame = asyncCallStacks[asyncOrdinal - 1];
         var ordinal = parsedCallFrameId["ordinal"];
         var callFrame = topCallFrame;