Tidy up ConsoleMessage callstack inclusion, fix Worker console crashes

Source/core/workers/WorkerConsole.cpp

Index: Source/core/workers/WorkerConsole.cpp
diff --git a/Source/core/workers/WorkerConsole.cpp b/Source/core/workers/WorkerConsole.cpp
index 7991d2814f048c1e14e09bd2d476ac00f7cd1635..6227d9d6290d15d803b5363b6aa25a50b6392175 100644
--- a/Source/core/workers/WorkerConsole.cpp
+++ b/Source/core/workers/WorkerConsole.cpp
@@ -51,9 +51,11 @@ WorkerConsole::~WorkerConsole()
 
 void WorkerConsole::reportMessageToConsole(PassRefPtrWillBeRawPtr<ConsoleMessage> consoleMessage)
 {
-    const ScriptCallFrame& lastCaller = consoleMessage->callStack()->at(0);
-    consoleMessage->setURL(lastCaller.sourceURL());
-    consoleMessage->setLineNumber(lastCaller.lineNumber());
+    if (RefPtrWillBeRawPtr<ScriptCallStack> callStack = consoleMessage->callStack()) {
+        const ScriptCallFrame& lastCaller = callStack->at(0);
+        consoleMessage->setURL(lastCaller.sourceURL());
+        consoleMessage->setLineNumber(lastCaller.lineNumber());
+    }

[kozyatinskiy1, 2014/09/15 12:57:25]

We have two places where we call this function: ConsoleBase::time/timeEnd and
internalAddMessage. If you add the collecting stack to time/timeEnd that I
missed then we do not need this check here. Because by default
createScriptCallStackForConsole and createScriptCallStackForConsole always
return at least one frame.

[sof, 2014/09/15 13:09:33]

That seems quite brittle - by inference, we should also remove it for the other
implementations of reportMessageToConsole() also? Which do not assume that a
callstack is present -- and should not afaict, as
createScriptCallStackForConsole() might return 0.

[kozyatinskiy1, 2014/09/15 13:31:29]

Ok, I agree with you but in this case, it is difficult to imagine a scenario in
which v8::Isolate would lose its context immediately after the console call and
createScriptCallStack* returns null.

     m_scope->addConsoleMessage(consoleMessage);
 }