Fix overflow in WriteQuoteJsonString and SlowQuoteJsonString

test/mjsunit/regress/regress-latin-1.js

Index: test/mjsunit/regress/regress-latin-1.js
diff --git a/test/mjsunit/regress/regress-latin-1.js b/test/mjsunit/regress/regress-latin-1.js
index b6cd7141a702dff897546306c564f5f50d468946..a9d895eeba3284372594881066d10c0ba2e81a5d 100644
--- a/test/mjsunit/regress/regress-latin-1.js
+++ b/test/mjsunit/regress/regress-latin-1.js
@@ -76,3 +76,15 @@ assertTrue(/[\u039b-\u039d]/i.test('\u00b5'));
 assertFalse(/[^\u039b-\u039d]/i.test('\u00b5'));
 assertFalse(/[\u039b-\u039d]/.test('\u00b5'));
 assertTrue(/[^\u039b-\u039d]/.test('\u00b5'));
+
+// Check a regression in QuoteJsonSlow and WriteQuoteJsonString
+for (var testNumber = 0; testNumber < 2; testNumber++) {
+  var testString = "\xdc";
+  var loopLength = testNumber == 0 ? 0 : 20;  
+  for (var i = 0; i < loopLength; i++ ) {
+    testString += testString;
+  }
+  var stringified = JSON.stringify({"test" : testString}, null, 0);
+  var stringifiedExpected = '{"test":"' + testString + '"}';
+  assertEquals(stringifiedExpected, stringified);
+}