Remove ExceptionState::throwIfNeeded

Remove ExceptionState::throwIfNeeded

ExceptionState should throw its pending exception when the ExceptionState gets destructed.
That way, caller sites don't need to call ExceptionState::throwIfNeeded every time.

BUG=

[haraken, 2016-06-14 11:42:45]

Description was changed from

==========
Remove ExceptionState::throwIfNeeded

BUG=
==========

to

==========
Remove ExceptionState::throwIfNeeded

ExceptionState should throw its pending exception when the ExceptionState gets
destructed.
That way, caller sites don't need to call ExceptionState::throwIfNeeded every
time.

BUG=
==========

[haraken, 2016-06-14 11:42:46]

haraken@chromium.org changed reviewers:
+ yukishiino@chromium.org

[haraken, 2016-06-14 11:43:58]

This is not yet for review, but # of failing tests are getting under control :)

[Yuki, 2016-06-15 07:23:25]

https://codereview.chromium.org/2061113002/diff/40001/third_party/WebKit/Sour...
File third_party/WebKit/Source/bindings/core/v8/ExceptionState.cpp (right):

https://codereview.chromium.org/2061113002/diff/40001/third_party/WebKit/Sour...
third_party/WebKit/Source/bindings/core/v8/ExceptionState.cpp:107:
clearException();
Why do you need this line?

throwException() is a private member function, and only the call site is the
destructor.  It seems more efficient to let the destructor of ScopedPersistent
clears things.

If it makes something clearer, I'd migrate the implementation of
throwException() into the destructor so that it's clear that no one else throws.
 Then, it's obvious that there is no need to do clearException().