Put RegExp js code in strict mode

test/webkit/fast/regex/lastIndex-expected.txt

Index: test/webkit/fast/regex/lastIndex-expected.txt
diff --git a/test/webkit/fast/regex/lastIndex-expected.txt b/test/webkit/fast/regex/lastIndex-expected.txt
index 1e0959c3f986cba7319ca62c189659193b671b80..71292c77b152882212e6c3a8b6212d6f69f47f08 100644
--- a/test/webkit/fast/regex/lastIndex-expected.txt
+++ b/test/webkit/fast/regex/lastIndex-expected.txt
@@ -42,10 +42,10 @@ PASS var re = Object.defineProperty(/x/, 'lastIndex', {value:42}); re.lastIndex
 PASS Object.defineProperty(Object.defineProperty(/x/, 'lastIndex', {writable:false}), 'lastIndex', {writable:true}); true threw exception TypeError: Cannot redefine property: lastIndex.
 PASS Object.defineProperty(Object.defineProperty(/x/, 'lastIndex', {writable:false}), 'lastIndex', {value:42}); true threw exception TypeError: Cannot redefine property: lastIndex.
 PASS Object.defineProperty(Object.defineProperty(/x/, 'lastIndex', {writable:false}), 'lastIndex', {value:0}); true is true
-PASS Object.defineProperty(/x/, 'lastIndex', {writable:false}).exec('') is null
+FAIL Object.defineProperty(/x/, 'lastIndex', {writable:false}).exec('') should be null. Threw exception TypeError: Cannot assign to read only property 'lastIndex' of object '[object RegExp]'
 PASS Object.defineProperty(/x/, 'lastIndex', {writable:false}).exec('x') is ["x"]
-FAIL Object.defineProperty(/x/g, 'lastIndex', {writable:false}).exec('') should throw an exception. Was null.
-FAIL Object.defineProperty(/x/g, 'lastIndex', {writable:false}).exec('x') should throw an exception. Was x.
+PASS Object.defineProperty(/x/g, 'lastIndex', {writable:false}).exec('') threw exception TypeError: Cannot assign to read only property 'lastIndex' of object '[object RegExp]'.
+PASS Object.defineProperty(/x/g, 'lastIndex', {writable:false}).exec('x') threw exception TypeError: Cannot assign to read only property 'lastIndex' of object '[object RegExp]'.
 PASS var re = /x/; Object.freeze(re); Object.isFrozen(re); is true
 PASS successfullyParsed is true