Simplify string copy in SubStringStub.

src/ia32/code-stubs-ia32.h

Index: src/ia32/code-stubs-ia32.h
diff --git a/src/ia32/code-stubs-ia32.h b/src/ia32/code-stubs-ia32.h
index ab60bc0c47ad874917fe817898c381984f8bef26..75adb1d5df9f9fe8e07e1c955a9479583481d8bb 100644
--- a/src/ia32/code-stubs-ia32.h
+++ b/src/ia32/code-stubs-ia32.h
@@ -40,12 +40,12 @@ class StringHelper : public AllStatic {
   // Generate code for copying characters using the rep movs instruction.
   // Copies ecx characters from esi to edi. Copying of overlapping regions is
   // not supported.
-  static void GenerateCopyCharactersREP(MacroAssembler* masm,
-                                        Register dest,     // Must be edi.
-                                        Register src,      // Must be esi.
-                                        Register count,    // Must be ecx.
-                                        Register scratch,  // Neither of above.
-                                        bool ascii);
+  static void GenerateCopyCharacters(MacroAssembler* masm,
+                                     Register dest,     // Must be edi.
+                                     Register src,      // Must be esi.
+                                     Register count,    // Must be ecx.
+                                     Register scratch,  // Neither of above.
+                                     String::Encoding encoding);
 
   // Generate string hash.
   static void GenerateHashInit(MacroAssembler* masm,