Remove obsolete JSFunction::IsOptimizable predicate.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 129c6c35ac9e58f09fc69b881a8c7c2ff1d22726..59960c70503b1aaa92c3ed55cf60d00c884ef7f0 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -7614,9 +7614,6 @@ class JSFunction: public JSObject {
   // Tells whether or not this function has been optimized.
   inline bool IsOptimized();
 
-  // Tells whether or not this function can be optimized.
-  inline bool IsOptimizable();
-
   // Mark this function for lazy recompilation. The function will be
   // recompiled the next time it is executed.
   void MarkForOptimization();