Merge a number of assertion failure fixes to the 3.0 branch.

src/ia32/macro-assembler-ia32.h

Index: src/ia32/macro-assembler-ia32.h
===================================================================
--- src/ia32/macro-assembler-ia32.h	(revision 6703)
+++ src/ia32/macro-assembler-ia32.h	(working copy)
@@ -539,6 +539,10 @@
 
   void Ret();
 
+  // Return and drop arguments from stack, where the number of arguments
+  // may be bigger than 2^16 - 1.  Requires a scratch register.
+  void Ret(int bytes_dropped, Register scratch);
+
   // Emit code to discard a non-negative number of pointer-sized elements
   // from the stack, clobbering only the esp register.
   void Drop(int element_count);