Clean up OwnPtr and PassOwnPtr in some of JS classes
https://bugs.webkit.org/show_bug.cgi?id=138724

Reviewed by Filip Pizlo.

As a step to use std::unique_ptr<> and std::make_unique<>, this patch replaces
OwnPtr with std::unique_ptr<>. Besides create() factory function is removed as well.

* builtins/BuiltinExecutables.h:
(JSC::BuiltinExecutables::create): Deleted.
* bytecode/CodeBlock.h:
(JSC::CodeBlock::createRareDataIfNecessary):
* bytecode/StructureStubInfo.h:
* bytecode/UnlinkedCodeBlock.h:
(JSC::UnlinkedCodeBlock::hasRareData):
(JSC::UnlinkedCodeBlock::createRareDataIfNecessary):
* runtime/CodeCache.cpp:
(JSC::CodeCache::getGlobalCodeBlock):
* runtime/CodeCache.h:
(JSC::CodeCache::create): Deleted.
* runtime/JSGlobalObject.cpp:
(JSC::JSGlobalObject::clearRareData):
* runtime/JSGlobalObject.h:
(JSC::JSGlobalObject::createRareDataIfNeeded):
* runtime/RegExpConstructor.h:
* runtime/SmallStrings.cpp:
(JSC::SmallStrings::createSingleCharacterString):
(JSC::SmallStrings::singleCharacterStringRep):
* runtime/SmallStrings.h:
* runtime/VM.cpp:
(JSC::VM::VM):
* runtime/VM.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@176508 268f45cc-cd09-0410-ab3c-d52691b4dbfc