Rename Match.str to input.

runtime/lib/regexp_patch.dart

Index: runtime/lib/regexp_patch.dart
diff --git a/runtime/lib/regexp_patch.dart b/runtime/lib/regexp_patch.dart
index 72b6f4bf827755d7465b50dab117aa45bef4a3cc..2fdee65e3a8c8ae9e323714b951c9c6c6e8bc4e0 100644
--- a/runtime/lib/regexp_patch.dart
+++ b/runtime/lib/regexp_patch.dart
@@ -3,10 +3,10 @@
 // BSD-style license that can be found in the LICENSE file.
 
 patch class RegExp {
-  /* patch */ factory RegExp(String pattern,
+  /* patch */ factory RegExp(String source,
                              {bool multiLine: false,
                               bool caseSensitive: true}) {
-    return new _JSSyntaxRegExp(pattern,
+    return new _JSSyntaxRegExp(source,
                                multiLine: multiLine,
                                caseSensitive: caseSensitive);
   }