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

Review URL: https://codereview.chromium.org/326853002

git-svn-id: svn://svn.chromium.org/blink/trunk@175862 bbb929c8-8fbe-4397-9dbb-9b2b20218538