Reviewed by Oliver Hunt.
        
        Fixed a small bit of https://bugs.webkit.org/show_bug.cgi?id=21962
        AST uses way too much memory
        
        Removed a word from StatementNode by nixing LabelStack and turning it
        into a compile-time data structure managed by CodeGenerator.
        
        v8 tests and SunSpider, run by Gavin, report no change.

        * GNUmakefile.am:
        * JavaScriptCore.order:
        * JavaScriptCore.pri:
        * JavaScriptCore.vcproj/JavaScriptCore/JavaScriptCore.vcproj:
        * JavaScriptCore.xcodeproj/project.pbxproj:
        * kjs/AllInOneFile.cpp:
        * JavaScriptCoreSources.bkl: I sure hope this builds!
        
        * VM/CodeGenerator.cpp:
        (JSC::CodeGenerator::CodeGenerator):
        (JSC::CodeGenerator::newLabelScope):
        (JSC::CodeGenerator::breakTarget):
        (JSC::CodeGenerator::continueTarget):
        * VM/CodeGenerator.h: Nixed the JumpContext system because it depended
        on a LabelStack in the AST, and it was a little cumbersome on the client
        side. Replaced with LabelScope, which tracks all break / continue
        information in the CodeGenerator, just like we track LabelIDs and other
        stacks of compile-time data.

        * kjs/LabelScope.h: Added.
        (JSC::LabelScope::):
        (JSC::LabelScope::LabelScope):
        (JSC::LabelScope::ref):
        (JSC::LabelScope::deref):
        (JSC::LabelScope::refCount):
        (JSC::LabelScope::breakTarget):
        (JSC::LabelScope::continueTarget):
        (JSC::LabelScope::type):
        (JSC::LabelScope::name):
        (JSC::LabelScope::scopeDepth): Simple abstraction for holding everything
        you might want to know about a break-able / continue-able scope.

        * kjs/LabelStack.cpp: Removed.
        * kjs/LabelStack.h: Removed.

        * kjs/grammar.y: No need to push labels at parse time -- we don't store
        LabelStacks in the AST anymore.

        * kjs/nodes.cpp:
        (JSC::DoWhileNode::emitCode):
        (JSC::WhileNode::emitCode):
        (JSC::ForNode::emitCode):
        (JSC::ForInNode::emitCode):
        (JSC::ContinueNode::emitCode):
        (JSC::BreakNode::emitCode):
        (JSC::SwitchNode::emitCode):
        (JSC::LabelNode::emitCode):
        * kjs/nodes.h:
        (JSC::StatementNode::):
        (JSC::LabelNode::): Use LabelScope where we used to use JumpContext.
        Simplified a bunch of code. Touched up label-related error messages a
        bit.

        * kjs/nodes2string.cpp:
        (JSC::LabelNode::streamTo): Updated for rename.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@38047 268f45cc-cd09-0410-ab3c-d52691b4dbfc