Revert "winrt: Skip context validation in ANGLE"

Our current ANGLE version (chromium/3280) relies on validation to be done
when doing the rendering, as the validation at the same time completes the
caching. Skipping the validation caused asserts and rendering issues.

The part of the validation that failed before is now deactivated in Qt's
copy of ANGLE as it is not relevant for our use case, so that validation
can be re-enabled now.

This reverts commit a1dec825f9.

Fixes: QTBUG-73317
Change-Id: I5fd176eaa0bc28d93ca93019b7092211fe5bcce5
Reviewed-by: Miguel Costa <miguel.costa@qt.io>
Reviewed-by: Andre de la Rocha <andre.rocha@qt.io>

src/plugins/platforms/winrt/qwinrteglcontext.cpp

@@ -138,7 +138,6 @@ void QWinRTEGLContext::initialize()
         EGL_CONTEXT_CLIENT_VERSION, d->format.majorVersion(),
         EGL_CONTEXT_MINOR_VERSION_KHR, d->format.minorVersion(),
         EGL_CONTEXT_FLAGS_KHR, flags,
-        EGL_CONTEXT_OPENGL_NO_ERROR_KHR, true,
         EGL_NONE
     };
     d->eglContext = eglCreateContext(g->eglDisplay, d->eglConfig, d->eglShareContext, attributes);