Introduce an OptimizingCompiler class, responsible for maintaining the state needed to run Crankshaft.

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Review URL: https://chromiumcodereview.appspot.com/10700188

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@12112 ce2b1a6d-e550-0410-aec6-3dcde31c8c00