Revert of Ensure DOMWrapperWorld always exists in all webkit_unit_tests (https://codereview.chromium.org/180743013/)

Reason for revert:
A few inspector tests are crashing:
WebCore::DOMWrapperWorld::ensureIsolatedWorld(int, int) [DOMWrapperWorld.cpp : 124 + 0x33]

Original issue's description:
> Ensure DOMWrapperWorld always exists in all webkit_unit_tests
> 
> Currently DOMWrapperWorld can be 0 in some tests. This is problematic since I want to make DOMWrapperWorld::current() callable from anywhere. Thus this CL adds DOMWrapperWorld to all webkit_unit_tests.
> 
> - It's verbose to initialize v8::HandleScope, v8::Context, v8::Context::Scope, V8PerContextData and DOMWrapperWorld in each test. So this CL adds a helper class (V8BindingTestScope) that does all the initialization work.
> 
> - This CL also fixes indentation of V8Binding.h.
> 
> BUG=341032
> NOTRY=true
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=168355

TBR=jochen@chromium.org,dcarney@chromium.org,haraken@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=341032

Review URL: https://codereview.chromium.org/183803017

git-svn-id: svn://svn.chromium.org/blink/trunk@168369 bbb929c8-8fbe-4397-9dbb-9b2b20218538