Implemented one-char cache lookup in generated code.

src/mips/codegen-mips.h

Index: src/mips/codegen-mips.h
diff --git a/src/mips/codegen-mips.h b/src/mips/codegen-mips.h
index c6abb8231c87b166877b55fc00b31d7b93423523..1d7c27452ac6eda50c51e9c25c256716c7633f7f 100644
--- a/src/mips/codegen-mips.h
+++ b/src/mips/codegen-mips.h
@@ -227,6 +227,9 @@ class CodeGenerator: public AstVisitor {
   // Fast support for charCodeAt(n).
   void GenerateFastCharCodeAt(ZoneList<Expression*>* args);
 
+  // Fast support for string.charAt(n) and string[n].
+  void GenerateCharFromCode(ZoneList<Expression*>* args);
+
   // Fast support for object equality testing.
   void GenerateObjectEquals(ZoneList<Expression*>* args);