Clean up Isolate usages in compilation cache.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 846debf5055aaa8f139608d6485d9a5c6dc0354f..824cc37118b6df9c64ff8b6edd3d066bf0777ea3 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -598,7 +598,7 @@ bool Isolate::PreInit() {
   string_tracker_->isolate_ = this;
   thread_manager_ = new ThreadManager();
   thread_manager_->isolate_ = this;
-  compilation_cache_ = new CompilationCache();
+  compilation_cache_ = new CompilationCache(this);
   transcendental_cache_ = new TranscendentalCache();
   keyed_lookup_cache_ = new KeyedLookupCache();
   context_slot_cache_ = new ContextSlotCache();