DevTools: defer styles delta calculation to until the end of the task.

Source/core/inspector/InspectorDebuggerAgent.cpp

 /*
  * Copyright (C) 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 1190 matching lines @@
             const String& localId = breakpointIterator->value.first;
             hitBreakpointIds->addItem(localId);
 
             BreakpointSource source = breakpointIterator->value.second;
             if (m_breakReason == InspectorFrontend::Debugger::Reason::Other && source == DebugCommandBreakpointSource)
                 m_breakReason = InspectorFrontend::Debugger::Reason::DebugCommand;
         }
     }
 
     m_frontend->paused(currentCallFrames(), m_breakReason, m_breakAuxData, hitBreakpointIds, currentAsyncStackTrace());
-    m_frontend->flush();
     m_javaScriptPauseScheduled = false;
 
     if (!m_continueToLocationBreakpointId.isEmpty()) {
         scriptDebugServer().removeBreakpoint(m_continueToLocationBreakpointId);
         m_continueToLocationBreakpointId = "";
     }
     if (m_listener)
         m_listener->didPause();
 }
 
@@ skipping 66 matching lines @@
     m_scripts.clear();
     m_breakpointIdToDebugServerBreakpointIds.clear();
     m_asyncCallStackTracker.clear();
     m_promiseTracker.clear();
     if (m_frontend)
         m_frontend->globalObjectCleared();
 }
 
 } // namespace WebCore