One instead of two runtime calls when initializing regexp.

src/jsregexp.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_JSREGEXP_H_
 #define V8_JSREGEXP_H_
 
 #include "src/allocation.h"
 #include "src/assembler.h"
 #include "src/zone-inl.h"
@@ skipping 28 matching lines @@
 
   // Returns a string representation of a regular expression.
   // Implements RegExp.prototype.toString, see ECMA-262 section 15.10.6.4.
   // This function calls the garbage collector if necessary.
   static Handle<String> ToString(Handle<Object> value);
 
   // Parses the RegExp pattern and prepares the JSRegExp object with
   // generic data and choice of implementation - as well as what
   // the implementation wants to store in the data field.
   // Returns false if compilation fails.
-  MUST_USE_RESULT static MaybeHandle<Object> Compile(
-      Handle<JSRegExp> re,
-      Handle<String> pattern,
-      Handle<String> flags);
+  MUST_USE_RESULT static MaybeHandle<Object> Compile(Handle<JSRegExp> re,
+                                                     Handle<String> pattern,
+                                                     JSRegExp::Flags flags);
 
   // See ECMA-262 section 15.10.6.2.
   // This function calls the garbage collector if necessary.
   MUST_USE_RESULT static MaybeHandle<Object> Exec(
       Handle<JSRegExp> regexp,
       Handle<String> subject,
       int index,
       Handle<JSArray> lastMatchInfo);
 
   // Prepares a JSRegExp object with Irregexp-specific data.
@@ skipping 1603 matching lines @@
                                    Handle<String> sample_subject,
                                    bool is_one_byte, Zone* zone);
 
   static void DotPrint(const char* label, RegExpNode* node, bool ignore_case);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_JSREGEXP_H_