Fix tst_qqmlecmascript::functionAssignment_fromBinding

Function declarations in QML mode should be similar to function expressions and
therefore need to go to the return value of the function..

Change-Id: Ib1dd8a970a967f2456d0558be74edf5d74d288e5
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Fix tst_qqmlecmascript::functionAssignment_fromJS

Make the test-case compile with strict mode, where function declarations
are not allowed within blocks. An alternative would be to use function
expressions here.

Change-Id: If7e1cc23ef4a0c6a83e4ba8ae03dc9c6b678730d
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Fix tst_qqmlecmascript::functionAssignment_afterBinding

When calling Qt.binding(f), don't modify f and set the bindingKeyFlag
there, but instead we must return a _new_ function that acts as proxy
and has the bindingKeyFlag set to true, similar to how the V8 based
implementation created a clone.

Change-Id: I4998359869c02e32c89e929793bf74a4adafcb72
Reviewed-by: Lars Knoll <lars.knoll@digia.com>