Revert of Add an ASSERT about cross-world wrapper leakage into ScriptValue

Revert of Add an ASSERT about cross-world wrapper leakage into ScriptValue (https://codereview.chromium.org/314953005/)

Reason for revert:
Causes many browser_tests to fail:
ActiveScriptControllerBrowserTest.*
ExtensionApiTest.ContentScript*
etc

Original issue's description:
> Add an ASSERT about cross-world wrapper leakage into ScriptValue
> 
> - This CL adds an ASSERT to ScriptValue to verify that ScriptValue::v8Value() is used in the same world that created the ScriptValue.
> 
> - To insert the check, we need to get a current world in ScriptValue::v8Value(). For that goal, this CL makes sure that we're in some context when calling ScriptValue::v8Value().
> 
> BUG=341032
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=175837

TBR=dcarney@chromium.org,adamk@chromium.org,jochen@chromium.org,tasak@google.com,abarth@chromium.org,haraken@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=341032
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=175862

[dcheng, 2014-06-10 06:08:30]

Created Revert of Add an ASSERT about cross-world wrapper leakage into
ScriptValue

[haraken, 2014-06-10 06:09:17]

LGTM, thanks for the revert!

[commit-bot: I haz the power, 2014-06-10 06:09:44]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/dcheng@chromium.org/326853002/1

[commit-bot: I haz the power, 2014-06-10 06:10:21]

Change committed as 175862