Improve the generated code for the instanceof operator.

src/macro-assembler-ia32.h

Index: src/macro-assembler-ia32.h
===================================================================
--- src/macro-assembler-ia32.h	(revision 469)
+++ src/macro-assembler-ia32.h	(working copy)
@@ -179,6 +179,16 @@
   void NegativeZeroTest(Register result, Register op1, Register op2,
                         Register scratch, Label* then_label);
 
+  // Try to get function prototype of a function and puts the value in
+  // the result register. Checks that the function really is a
+  // function and jumps to the miss label if the fast checks fail. The
+  // function register will be untouched; the other registers may be
+  // clobbered.
+  void TryGetFunctionPrototype(Register function,
+                               Register result,
+                               Register scratch,
+                               Label* miss);
+
   // Generates code for reporting that an illegal operation has
   // occurred.
   void IllegalOperation(int num_arguments);