Teach more WTF string classes about vectors with inline capacity
https://bugs.webkit.org/show_bug.cgi?id=109617

Reviewed by Benjamin Poulain.

The HTML and WebVTT parsers use constructions like:
AtomicString name(m_name.data(), m_name.size())
all over the place because they use inline capacity
on the parse vectors for performance.

This change just add the necessary template variants
to the related String constructors/methods in WTF so that
this parser code can just pass the vector directly instead.

I'll do the actual parser cleanups in follow-up patches to keep things simple.

* wtf/text/AtomicString.h:
(AtomicString):
(WTF::AtomicString::AtomicString):
* wtf/text/StringImpl.h:
(StringImpl):
(WTF::StringImpl::create8BitIfPossible):
* wtf/text/WTFString.h:
(String):
(WTF::String::make8BitFrom16BitSource):
(WTF):
(WTF::append):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@142689 268f45cc-cd09-0410-ab3c-d52691b4dbfc