Fix paint invalidation rect tracking within composited scrolling layers.

LayoutTests/platform/linux/compositing/repaint/should-not-clip-composited-overflow-scrolling-layer-expected.txt

Index: LayoutTests/platform/linux/compositing/repaint/should-not-clip-composited-overflow-scrolling-layer-expected.txt
diff --git a/LayoutTests/platform/linux/compositing/repaint/should-not-clip-composited-overflow-scrolling-layer-expected.txt b/LayoutTests/platform/linux/compositing/repaint/should-not-clip-composited-overflow-scrolling-layer-expected.txt
index 19c0efb02aa0ae62e5c3492aa0acf540a2bd4e81..a297a9553e410415a8fe504e90621bb57ba3f2ea 100644
--- a/LayoutTests/platform/linux/compositing/repaint/should-not-clip-composited-overflow-scrolling-layer-expected.txt
+++ b/LayoutTests/platform/linux/compositing/repaint/should-not-clip-composited-overflow-scrolling-layer-expected.txt
@@ -11,23 +11,10 @@
           "bounds": [500, 500],
           "drawsContent": true,
           "repaintRects": [
-            [0, 20, 821, 19],
-            [0, 0, 5000, 5000],
-            [0, 0, 801, 19],
-            [-2000, -1980, 821, 19],
-            [-2000, -2000, 5000, 5000],
-            [-2000, -2000, 801, 19]
+            [-2000, -2000, 5000, 5000]
           ],
           "paintInvalidationClients": [
-            "LayoutBlockFlow DIV id='content'",
-            "LayoutText #text",
-            "InlineTextBox 'Tests invalidation of scrolling layer. Passes if the repaint rect is not clipped,\n'",
-            "InlineTextBox 'and there is no red when the scrolling container is scrolled.'",
-            "LayoutBR BR",
-            "InlineTextBox '\n'",
-            "LayoutText #text",
-            "InlineTextBox 'Note for manual testing: must run with --enable-prefer-compositing-to-lcd-text\n'",
-            "InlineTextBox 'on non-high-dpi machines to enable composited scrolling.'"
+            "LayoutBlockFlow DIV id='content'"
           ],
           "children": [
             {
@@ -37,23 +24,10 @@
                   "bounds": [5000, 5000],
                   "drawsContent": true,
                   "repaintRects": [
-                    [2000, 2020, 821, 19],
-                    [2000, 2000, 5000, 5000],
-                    [2000, 2000, 801, 19],
-                    [0, 20, 821, 19],
-                    [0, 0, 5000, 5000],
-                    [0, 0, 801, 19]
+                    [0, 0, 5000, 5000]
                   ],
                   "paintInvalidationClients": [
-                    "LayoutBlockFlow DIV id='content'",
-                    "LayoutText #text",
-                    "InlineTextBox 'Tests invalidation of scrolling layer. Passes if the repaint rect is not clipped,\n'",
-                    "InlineTextBox 'and there is no red when the scrolling container is scrolled.'",
-                    "LayoutBR BR",
-                    "InlineTextBox '\n'",
-                    "LayoutText #text",
-                    "InlineTextBox 'Note for manual testing: must run with --enable-prefer-compositing-to-lcd-text\n'",
-                    "InlineTextBox 'on non-high-dpi machines to enable composited scrolling.'"
+                    "LayoutBlockFlow DIV id='content'"
                   ],
                   "children": [
                     {