Bug 1423282 - Remove aliveCheck to frame message manager. r=automatedtester

The IPC message "aliveCheck" will always fail because there is no such
message handler in Marionette and because it swallows all thrown errors.

MozReview-Commit-ID: JISuK65ZcGM

--HG--
extra : rebase_source : e4ccbb96727a67ce11f31463a08f66768bd23589

testing/marionette/frame.js

@@ -80,14 +80,6 @@ frame.Manager = class {
     for (let i = 0; i < this.remoteFrames.length; i++) {
       let f = this.remoteFrames[i];
       let fmm = f.messageManager.get();
-      try {
-        fmm.sendAsyncMessage("aliveCheck", {});
-      } catch (e) {
-        if (e.result == Cr.NS_ERROR_NOT_INITIALIZED) {
-          this.remoteFrames.splice(i--, 1);
-          continue;
-        }
-      }
 
       if (fmm == mm) {
         this.currentRemoteFrame = f;