Improve handling of failed integer type conversions.

LayoutTests/storage/indexeddb/exceptions-expected.txt

 Test that expected exceptions are thrown per IndexedDB spec.
 
 On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
 
 
 indexedDB = self.indexedDB || self.webkitIndexedDB || self.mozIndexedDB || self.msIndexedDB || self.OIndexedDB;
 
 dbname = "exceptions.html"
 indexedDB.deleteDatabase(dbname)
 indexedDB.open(dbname)
@@ skipping 427 matching lines @@
 request = transaction.objectStore('store').openCursor(IDBKeyRange.lowerBound(-Infinity), 'prev')
 reverseCursor = request.result
 request = transaction.objectStore('inlineKeyStore').openCursor()
 inlineCursor = request.result
 
 IDBCursor.advance()
 Calling this method more than once before new cursor data has been loaded is not allowed and results in a DOMException of type InvalidStateError being thrown.
 If the value for count is 0 (zero) or a negative number, this method must throw a JavaScript TypeError exception.
 Expecting TypeError exception from cursor.advance(0)
 PASS Exception was thrown.
-PASS cursor.advance(0) threw TypeError: Type error
+PASS cursor.advance(0) threw TypeError: Failed to execute 'advance' on 'IDBCursor': A count argument with value 0 (zero) was supplied, must be greater than 0.
 cursor.advance(1)
 Expecting exception from cursor.advance(1)
 PASS Exception was thrown.
 PASS code is DOMException.INVALID_STATE_ERR
 PASS ename is 'InvalidStateError'
 Exception message: Failed to execute 'advance' on 'IDBCursor': The cursor is being iterated or has iterated past its end.
 The transaction this IDBCursor belongs to is not active.
 Expecting exception from cursorFromInactiveTransaction.advance(1)
 PASS Exception was thrown.
 PASS code is 0
@@ skipping 103 matching lines @@
 If the requested object store is not in this transaction's scope.
 Expecting exception from db.transaction('store').objectStore('otherStore')
 PASS Exception was thrown.
 PASS code is DOMException.NOT_FOUND_ERR
 PASS ename is 'NotFoundError'
 Exception message: Failed to execute 'objectStore' on 'IDBTransaction': The specified object store was not found.
 PASS successfullyParsed is true
 
 TEST COMPLETE