This implements the parts of the "prepare a script element" algorithm that are
required for synchronous scripts. It also adds some infrastructure for future
support of the `async` and `defer` attributes.
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