Revert of Revert of DevTools: do not mute the protocol channel while reattaching.

Source/web/WebDevToolsAgentImpl.cpp

Index: Source/web/WebDevToolsAgentImpl.cpp
diff --git a/Source/web/WebDevToolsAgentImpl.cpp b/Source/web/WebDevToolsAgentImpl.cpp
index 29d8936cef850d876cd3b5d52dcd64a1793ab4a8..30856a69139a0004cea1cac5ca0c6f4835a09810 100644
--- a/Source/web/WebDevToolsAgentImpl.cpp
+++ b/Source/web/WebDevToolsAgentImpl.cpp
@@ -240,19 +240,21 @@
     if (m_attached)
         return;
 
+    // Set the attached bit first so that sync notifications were delivered.
+    m_attached = true;
     inspectorController()->connectFrontend(hostId, this);
     Platform::current()->currentThread()->addTaskObserver(this);
+}
+
+void WebDevToolsAgentImpl::reattach(const WebString& hostId, const WebString& savedState)
+{
+    if (m_attached)
+        return;
+
+    // Set the attached bit first so that sync notifications were delivered.
     m_attached = true;
-}
-
-void WebDevToolsAgentImpl::reattach(const WebString& hostId, const WebString& savedState)
-{
-    if (m_attached)
-        return;
-
     inspectorController()->reuseFrontend(hostId, this, savedState);
     Platform::current()->currentThread()->addTaskObserver(this);
-    m_attached = true;
 }
 
 void WebDevToolsAgentImpl::detach()