Remove worker support of Web SQL Database.

LayoutTests/fast/workers/storage/resources/transaction-in-transaction-sync.js

-var db = openDatabaseSync("TransactionInTransactionTest", "1.0", "Test that trying to run a nested transaction fails.", 1);
-db.transaction(function(tx) {
-    try {
-        db.transaction(function(nestedTx) { });
-        postMessage("FAIL: Trying to run a nested transaction should throw an exception." + db.lastErrorMessage);
-    } catch (err) {
-        postMessage("PASS: Exception thrown while trying to run a nested transaction (" + db.lastErrorMessage + ").");
-    }
-});
-
-postMessage("done");