Add source file and line number to QV4::Exception

This will allow us to replace v8::Message properly and give
us proper error reporting for uncaught exceptions.

Change-Id: I1c03b6c21456dea06931a874bb2aa5a0b00aff62
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Cleanup QQmlDelayedError

Remove dependency onto v8::Message and simplify conversion from
QV4::Exception to QQmlError.

Change-Id: Icfdfd7a2749210b2df9fda6cd5de94114b8adcfa
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Fix return value for QQmlJavascriptExpression::evaluate

Change-Id: Idf95ee51b7d50682476371c7f49537930fdf96f1
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>
Remove half the v8::TryCatch statements

Replacing the other half requires a replacement for v8::Script.

Change-Id: I40fe99302fba23f286773ec1adaf8d3751db901d
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>