X64: Change strategy for spilling to match ia32. It's just better.

src/x64/assembler-x64.h

Index: src/x64/assembler-x64.h
diff --git a/src/x64/assembler-x64.h b/src/x64/assembler-x64.h
index 4b4b8db142ce807a74480a15c59eb27d42162899..f195439eba9f91866206bff06362edc2e0a28a2c 100644
--- a/src/x64/assembler-x64.h
+++ b/src/x64/assembler-x64.h
@@ -499,6 +499,8 @@ class Assembler : public Malloced {
   // possible to align the pc offset to a multiple
   // of m. m must be a power of 2.
   void Align(int m);
+  // Aligns code to something that's optimal for a jump target for the platform.
+  void CodeTargetAlign();
 
   // Stack
   void pushfq();