[Qt] Allow to use WebCore imagedecoders

[Qt] Allow to use WebCore imagedecoders
https://bugs.webkit.org/show_bug.cgi?id=32410

Source/WebCore:

Add ENABLE(QT_IMAGE_DECODER) guards around Qt imagedecoders and set it to default.
By passing ENABLE_QT_IMAGE_DECODER=0 define to the build system WebKit will build
with WebCore's imagedecoders.

I added NO_RETURN attribute to 2 functions of PNG and JPEG decoders to avoid compiler warnings
because in Qt-port we treat warning as errors (-Werror).

I'm continuing the refactoring of this area and try to use Qt imagedecoders only in
cases when WebCore doesn't support the image format.

Reviewed by Simon Hausmann.

No behavior change, no need new tests.

* Target.pri:
* WebCore.pri:
* platform/MIMETypeRegistry.cpp:
(WebCore::initializeSupportedImageMIMETypes):
(WebCore::initializeSupportedImageMIMETypesForEncoding):
* platform/image-decoders/ImageDecoder.h:
(WebCore::ImageFrame::getAddr):
(ImageFrame):
* platform/image-decoders/jpeg/JPEGImageDecoder.cpp:
NO_RETURN has been added to a function to avoid warning message.
* platform/image-decoders/png/PNGImageDecoder.cpp:
NO_RETURN has been added to a function to avoid warning message.
(WebCore):
* platform/image-decoders/qt/ImageFrameQt.cpp:
(WebCore):
(WebCore::ImageFrame::asNewNativeImage):

Tools:

Add ENABLE_QT_IMAGE_DECODER macro, it's enabled by default.

Reviewed by Simon Hausmann.

* qmake/mkspecs/features/features.prf:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@108685 268f45cc-cd09-0410-ab3c-d52691b4dbfc