Revert of Have postMessage()s throw TypeError on failed arity checks.

Revert of Have postMessage()s throw TypeError on failed arity checks. (patchset #2 id:20001 of https://codereview.chromium.org/1025203002/)

Reason for revert:
Broke org.chromium.android_webview.test.PostMessageTest#testPostUnsupportedWebMessageToApp

http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_android_rel_ng/builds/4331/steps/Instrumentation%20test%20AndroidWebViewTest%20%28with%20patch%29/logs/stdio

Original issue's description:
> Have postMessage()s throw TypeError on failed arity checks.
> 
> R=haraken,mkwst@chromium.org
> BUG=339441
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=192337

TBR=mkwst@chromium.org,haraken@chromium.org,jsbell@chromium.org,sigbjornf@opera.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=339441
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=192364

[dglazkov, 2015-03-23 15:05:19]

Created Revert of Have postMessage()s throw TypeError on failed arity checks.

[commit-bot: I haz the power, 2015-03-23 15:05:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1033443002/1

[commit-bot: I haz the power, 2015-03-23 15:06:00]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=192364

[haraken, 2015-03-23 15:09:34]

LGTM

[sof, 2015-03-23 16:24:21]

lgtm, thanks for reverting.

The problematic call being
https://code.google.com/p/chromium/codesearch#chromium/src/android_webview/ja...