hasIndexingHeader() ought really to be a property of an object and its structure, not just its structure
https://bugs.webkit.org/show_bug.cgi?id=119470

Reviewed by Oliver Hunt.
        
Structure can still tell you if the object "could" (in the conservative sense)
have an indexing header; that's used by the compiler.
        
Most of the time if you want to know if there's an indexing header, you ask the
JSObject.
        
In some cases, the JSObject wants to know if it would have an indexing header if
it had a different structure; then it uses Structure::hasIndexingHeader(JSCell*).

* dfg/DFGRepatch.cpp:
(JSC::DFG::tryCachePutByID):
(JSC::DFG::tryBuildPutByIdList):
* dfg/DFGSpeculativeJIT.cpp:
(JSC::DFG::SpeculativeJIT::compileAllocatePropertyStorage):
(JSC::DFG::SpeculativeJIT::compileReallocatePropertyStorage):
* runtime/ButterflyInlines.h:
(JSC::Butterfly::create):
(JSC::Butterfly::growPropertyStorage):
(JSC::Butterfly::growArrayRight):
(JSC::Butterfly::resizeArray):
* runtime/JSObject.cpp:
(JSC::JSObject::copyButterfly):
(JSC::JSObject::visitButterfly):
* runtime/JSObject.h:
(JSC::JSObject::hasIndexingHeader):
(JSC::JSObject::setButterfly):
* runtime/Structure.h:
(JSC::Structure::couldHaveIndexingHeader):
(JSC::Structure::hasIndexingHeader):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@153691 268f45cc-cd09-0410-ab3c-d52691b4dbfc