Fix warnings in declarative tests.

Fix warnings in declarative tests.

- Unused variables and test data.
- () around operator &&.
- Conversion of false to 0-pointer where QVariant was intended.
- Missing enumeration value.
- Remove duplicated  qqmlecmascript entry from qml.pro
  (has an internal check for no-widgets).

Change-Id: Ie030167e22bce26e3988a4406c630fb460f61a3c
Reviewed-by: Jason McDonald <jason.mcdonald@nokia.com>