returning a null (err, empty-ish) string.  Move String::replaceRange
and String::spliceSubstringsWithSeparators out to StringPrototype -
these were fairly specific use anyway, and we can better integrate
throwing the JS expcetion this way.

Reviewed by Oliver Hunt

Also removes redundant assignment operator from UString.

* JavaScriptCore.exp:
* runtime/StringPrototype.cpp:
(JSC::StringRange::StringRange):
(JSC::jsSpliceSubstringsWithSeparators):
(JSC::jsReplaceRange):
(JSC::stringProtoFuncReplace):
* runtime/UString.cpp:
* runtime/UString.h:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@54531 268f45cc-cd09-0410-ab3c-d52691b4dbfc