Port of changes from r3842 (symbol table probing for two character strings) t...

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
===================================================================
--- src/x64/macro-assembler-x64.h	(revision 4029)
+++ src/x64/macro-assembler-x64.h	(working copy)
@@ -426,6 +426,20 @@
                                            Register scratch2,
                                            Label* on_not_both_flat_ascii);
 
+  // Check whether the instance type represents a flat ascii string. Jump to the
+  // label if not. If the instance type can be scratched specify same register
+  // for both instance type and scratch.
+  void JumpIfInstanceTypeIsNotSequentialAscii(Register instance_type,
+                                              Register scratch,
+                                              Label *on_not_flat_ascii_string);
+
+  void JumpIfBothInstanceTypesAreNotSequentialAscii(
+      Register first_object_instance_type,
+      Register second_object_instance_type,
+      Register scratch1,
+      Register scratch2,
+      Label* on_fail);
+
   // ---------------------------------------------------------------------------
   // Macro instructions.