Fix for issues introduced in r80667.

Reviewed by Sam Weinig.

Source/JavaScriptCore: 

Invalid flags to a RegExp literal are a late syntax error!

* bytecode/CodeBlock.h:
(JSC::CodeBlock::addRegExp):
    - Pass a PassRefPtr<RegExp>
* bytecompiler/BytecodeGenerator.cpp:
(JSC::BytecodeGenerator::addRegExp):
(JSC::BytecodeGenerator::emitNewRegExp):
* bytecompiler/BytecodeGenerator.h:
    - Pass a PassRefPtr<RegExp>
* bytecompiler/NodesCodegen.cpp:
(JSC::RegExpNode::emitBytecode):
    - Should not be ASSERTing that the flags are valid - this is a late(er) error.
* interpreter/Interpreter.cpp:
(JSC::Interpreter::privateExecute):
    - Need to check for error from RegExp constructor.
* jit/JITStubs.cpp:
(JSC::DEFINE_STUB_FUNCTION):
    - Need to check for error from RegExp constructor.
* runtime/RegExp.h:
(JSC::RegExp::isValid):
    - Make isValid check that the regexp was created with valid flags.
* runtime/RegExpKey.h:
    - Since we'll not create RegExp objects with invalid flags, separate out the deleted value.

LayoutTests: 

* fast/regex/script-tests/parentheses.js:
* fast/regex/script-tests/pcre-test-1.js:
    - Providing invalid flags to RegExp literals is an error in ES5.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@80684 268f45cc-cd09-0410-ab3c-d52691b4dbfc