Correctly reset lastIndex in an RegExp object.

test/mjsunit/regress/regress-crbug-170856.js

Index: test/mjsunit/regress/regress-crbug-170856.js
diff --git a/test/message/regress/regress-73.js b/test/mjsunit/regress/regress-crbug-170856.js
similarity index 89%
copy from test/message/regress/regress-73.js
copy to test/mjsunit/regress/regress-crbug-170856.js
index 72652d74a9e71c7858958c580ff44f02cea25a44..2e73b12caaf78c8b070c243ee79d3b8e557ad97d 100644
--- a/test/message/regress/regress-73.js
+++ b/test/mjsunit/regress/regress-crbug-170856.js
@@ -1,4 +1,4 @@
-// Copyright 2008 the V8 project authors. All rights reserved.
+// Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
@@ -25,9 +25,9 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-try {
-  throw 'a';
-} catch (e) {
-  throw 'b';
-  print('c');
-}
+r = new RegExp("a");
+for (var i = 0; i < 100; i++) {
+  r["abc" + i] = i;
+}
+"zzzz".replace(r, "");
+assertEquals(0, r.lastIndex);