Set the Lexer into qml mode when parsing binding expressions

Set the Lexer into qml mode when parsing binding expressions

Binding expressions allow multiline strings and digits starting
with 0. Simply setting the lexer into qmlmode when parsing them
will allow these expressions to pass.

Fixes 3 more test failures in qqmlecmascript

Change-Id: Ia14ec6d3facaf31883bb824c57096e59df3efea2
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>