Remove frame flattening support as Chromium has no intention of using it

LayoutTests/fast/frames/flattening/iframe-tiny-expected.txt

Index: LayoutTests/fast/frames/flattening/iframe-tiny-expected.txt
diff --git a/LayoutTests/fast/frames/flattening/iframe-tiny-expected.txt b/LayoutTests/fast/frames/flattening/iframe-tiny-expected.txt
deleted file mode 100644
index e1075b8f78364e5e5a128f44219a319f272516cd..0000000000000000000000000000000000000000
--- a/LayoutTests/fast/frames/flattening/iframe-tiny-expected.txt
+++ /dev/null
@@ -1,45 +0,0 @@
-Test that frame flattening is not used for tiny frames. This test requires DRT or user agent with flattening enabled.
-
-On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
-
-
-testFrame0
-PASS getComputedStyle(frame, 0).width is '0px'
-PASS getComputedStyle(frame, 0).height is '0px'
-testFrame1
-PASS getComputedStyle(frame, 0).width is '1px'
-PASS getComputedStyle(frame, 0).height is '1px'
-testFrame2
-PASS getComputedStyle(frame, 0).width is '7px'
-PASS getComputedStyle(frame, 0).height is '7px'
-testFrame3
-PASS getComputedStyle(frame, 0).width is '400px'
-PASS getComputedStyle(frame, 0).height is '400px'
-testFrame4
-PASS getComputedStyle(frame, 0).width is '0px'
-PASS getComputedStyle(frame, 0).height is '100px'
-testFrame5
-PASS getComputedStyle(frame, 0).width is '100px'
-PASS getComputedStyle(frame, 0).height is '0px'
-testFrame6
-PASS getComputedStyle(frame, 0).width is '100px'
-PASS getComputedStyle(frame, 0).height is '2px'
-testFrame7
-PASS getComputedStyle(frame, 0).width is '2px'
-PASS getComputedStyle(frame, 0).height is '100px'
-testFrame8
-PASS getComputedStyle(frame, 0).width is '2px'
-PASS getComputedStyle(frame, 0).height is '150px'
-testFrame9
-PASS getComputedStyle(frame, 0).width is '300px'
-PASS getComputedStyle(frame, 0).height is '2px'
-testFrame10
-PASS getComputedStyle(frame, 0).width is '400px'
-PASS getComputedStyle(frame, 0).height is '400px'
-testFrame11
-PASS getComputedStyle(frame, 0).width is '400px'
-PASS getComputedStyle(frame, 0).height is '400px'
-PASS successfullyParsed is true
-
-TEST COMPLETE
-