Properly find Frame from Node context

or debug callback can't get the listener.
Fix rogerwang/node-webkit#719

#0  WebCore::InspectorDebuggerAgent::didPause (this=0x7ffff7ee8800,
    scriptState=0x192e07eebb10, callFrames=..., exception=...)
    at ../../third_party/WebKit/Source/core/inspector/InspectorDebuggerAgent.cpp:682
#1  0x0000000003665f7e in WebCore::ScriptDebugServer::breakProgram (
    this=0x7ffff7ee8260, executionState=..., exception=...)
    at ../../third_party/WebKit/Source/bindings/v8/ScriptDebugServer.cpp:425
#2  0x0000000003666ceb in WebCore::ScriptDebugServer::handleV8DebugEvent (
    this=0x7ffff7ee8260, eventDetails=...)
    at ../../third_party/WebKit/Source/bindings/v8/ScriptDebugServer.cpp:503
#3  0x0000000003666012 in WebCore::ScriptDebugServer::v8DebugEventCallback (
    eventDetails=...)
    at ../../third_party/WebKit/Source/bindings/v8/ScriptDebugServer.cpp:435
#4  0x0000000000f7ecb3 in v8::internal::Debugger::CallCEventCallback (
    this=0x7ffff7eec520, event=v8::Break, exec_state=..., event_data=...,
    client_data=0x0) at ../../v8/src/debug.cc:2953
#5  0x0000000000f7ebf9 in v8::internal::Debugger::CallEventCallback (
    this=0x7ffff7eec520, event=v8::Break, exec_state=..., event_data=...,
    client_data=0x0) at ../../v8/src/debug.cc:2932
#6  0x0000000000f7eabd in v8::internal::Debugger::ProcessDebugEvent (
    this=0x7ffff7eec520, event=v8::Break, event_data=..., auto_continue=false)
    at ../../v8/src/debug.cc:2909
#7  0x0000000000f7e24d in v8::internal::Debugger::OnDebugBreak (
    this=0x7ffff7eec520, break_points_hit=..., auto_continue=false)
    at ../../v8/src/debug.cc:2750
#8  0x0000000000f7836f in v8::internal::Debug::Break (this=0x7ffff7eecc20,
    args=...) at ../../v8/src/debug.cc:992
#9  0x0000000000f787a8 in v8::internal::__RT_impl_Debug_Break (args=...,
    isolate=0x7ffff7e80020) at ../../v8/src/debug.cc:1062
#10 0x0000000000f78769 in v8::internal::Debug_Break (args_length=0,
    args_object=0x7fffffff8248, isolate=0x7ffff7e80020)
    at ../../v8/src/debug.cc:1061