Enable optimization of top-level code.

src/compiler.h

Index: src/compiler.h
===================================================================
--- src/compiler.h	(revision 10686)
+++ src/compiler.h	(working copy)
@@ -163,11 +163,6 @@
     flags_ |= SupportsDeoptimization::encode(true);
   }
 
-  // Determine whether or not we can adaptively optimize.
-  bool AllowOptimize() {
-    return V8::UseCrankshaft() && !closure_.is_null();
-  }
-
   // Determines whether or not to insert a self-optimization header.
   bool ShouldSelfOptimize();
 
@@ -181,9 +176,8 @@
   // Compilation mode.
   // BASE is generated by the full codegen, optionally prepared for bailouts.
   // OPTIMIZE is optimized code generated by the Hydrogen-based backend.
-  // NONOPT is generated by the full codegen or the classic backend
-  //   and is not prepared for recompilation/bailouts. These functions
-  //   are never recompiled.
+  // NONOPT is generated by the full codegen and is not prepared for
+  //   recompilation/bailouts.  These functions are never recompiled.
   enum Mode {
     BASE,
     OPTIMIZE,