Reviewed by Antonio Gomes.

        Convert layout test fast/frame/frame-src-attribute.html from
        render-tree/pixel test to text-only test
        https://bugs.webkit.org/show_bug.cgi?id=48200

        Modified the test case LayoutTests/fast/frame/frame-src-attribute.html
        to dump its output as text.

        Currently, the test produces a render-tree dump. Instead, it is sufficient
        for this test to dump as text since it is a PASS/FAIL-style test. This will
        also make the test results platform-independent.

        * fast/frames/frame-src-attribute-expected.txt: Added.
        * fast/frames/frame-src-attribute.html: Modified to dump its output as text.
        * platform/chromium-linux/fast/frames/frame-src-attribute-expected.checksum: Removed.
        * platform/chromium-linux/fast/frames/frame-src-attribute-expected.png: Removed.
        * platform/chromium-mac/fast/frames/frame-src-attribute-expected.checksum: Removed.
        * platform/chromium-mac/fast/frames/frame-src-attribute-expected.png: Removed.
        * platform/chromium-win/fast/frames/frame-src-attribute-expected.checksum: Removed.
        * platform/chromium-win/fast/frames/frame-src-attribute-expected.png: Removed.
        * platform/chromium-win/fast/frames/frame-src-attribute-expected.txt: Removed.
        * platform/gtk/fast/frames/frame-src-attribute-expected.txt: Removed.
        * platform/mac/fast/frames/frame-src-attribute-expected.checksum: Removed.
        * platform/mac/fast/frames/frame-src-attribute-expected.png: Removed.
        * platform/mac/fast/frames/frame-src-attribute-expected.txt: Removed.
        * platform/qt/fast/frames/frame-src-attribute-expected.txt: Removed.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@70416 268f45cc-cd09-0410-ab3c-d52691b4dbfc