Remove worker support of Web SQL Database.

LayoutTests/fast/workers/storage/resources/empty-statement-sync.js

-try {
-    var db = openDatabaseSync("EmptyStatementSync", "1.0", "Test an empty statement.", 1);
-    db.transaction(function(tx) {
-        var result = tx.executeSql("");
-        postMessage(result ? "FAIL: result is not null" : "PASS: result is null");
-    });
-    postMessage("PASS");
-} catch (err) {
-    postMessage("FAIL");
-}
-
-postMessage("done");