Adding initial version of parser trait

Added parse_chunk method declaration to parser

Removed unnecessary visibilty for parse_chunk function

Implemented parse_chunk function

Implemented parse_chunk fn for ServoHTMLParser

Moved parser trait to mod.rs and added finish fn

added licence header to mod.rs and other review comments

Fixed trailing space issue

Fixed failed tabular space test

components/script/parse/mod.rs

@@ -0,0 +1,10 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+pub mod html;
+
+pub trait Parser {
+    fn parse_chunk(&self,input: String);
+    fn finish(&self);
+}