RN: Clear Debug Console on Reload JS

Summary:
Clears the debug console whenever the React Native JS is reloaded.

NOTE: This respects "Preserve log" in Chrome by default.

Reviewed By: jingc

Differential Revision: D3409713

fbshipit-source-id: ce215e3125cf43ab3ea5811c707fab9dfa4bcbb3

local-cli/server/util/debugger.html

@@ -72,6 +72,7 @@ function connectToDebuggerProxy() {
     // Special message that asks for a new JS runtime
     if (object.method === 'prepareJSRuntime') {
       shutdownJSRuntime();
+      console.clear();
       createJSRuntime();
       ws.send(JSON.stringify({replyID: object.id}));
       setStatus('Debugger session #' + object.id + ' active.');