Enable slimming paint for fast/repaint

LayoutTests/platform/mac/fast/repaint/line-flow-with-floats-2-expected.txt

 {
   "bounds": [800, 600],
   "children": [
     {
       "bounds": [800, 600],
       "contentsOpaque": true,
       "drawsContent": true,
       "repaintRects": [
         [372, 375, 48, 80],
         [372, 371, 48, 80],
@@ skipping 13 matching lines @@
         [14, 353, 48, 64],
         [14, 246, 406, 126],
         [14, 242, 406, 126],
         [14, 191, 407, 73],
         [14, 188, 407, 72],
         [14, 188, 45, 22],
         [14, 188, 41, 18],
         [8, 572, 418, 4],
         [8, 569, 418, 7],
         [8, 170, 418, 400]
+      ],
+      "paintInvalidationClients": [
+        "InlineTextBox 'going to give the hedgehog a blow with its head, it'",
+        "RootInlineBox",
+        "InlineTextBox ''",
+        "InlineTextBox ' twist itself round and look up in her face, with\n'",
+        "InlineTextBox 'such a'",
+        "RootInlineBox",
+        "LayoutBlockFlow P",
+        "LayoutBlockFlow P",
+        "LayoutInline I id='would'",
+        "LayoutText #text",
+        "InlineTextBox 'would'",
+        "LayoutText #text",
+        "InlineTextBox ' twist itself round and look up in her face, with\n'",
+        "InlineTextBox 'such a'",
+        "InlineTextBox 'puzzled expression that she could not help bursting out'",
+        "InlineTextBox 'laughing: and when she had got its head down, and was going'",
+        "InlineTextBox 'to\n'",
+        "LayoutText #text",
+        "InlineTextBox 'begin again, it was very provoking to find that the hedgehog'",
+        "InlineTextBox 'had\n'",
+        "InlineTextBox 'unrolled itself, and was in the act of crawling away:'",
+        "InlineTextBox 'besides all\n'",
+        "InlineTextBox 'this, there was generally a ridge or furrow in the'",
+        "InlineTextBox 'way wherever\n'",
+        "InlineTextBox 'she wanted to send the hedgehog to, and, as the'",
+        "InlineTextBox 'doubled-up\n'",
+        "InlineTextBox 'soldiers were always getting up and walking off to'",
+        "InlineTextBox 'other parts of\n'",
+        "InlineTextBox 'the ground, Alice soon came to the conclusion'",
+        "InlineTextBox 'that it was a very\n'",
+        "LayoutBlockFlow (floating) SPAN id='blueFloat'",
+        "LayoutText #text",
+        "InlineTextBox 'difficult game indeed.\n'",
+        "LayoutText #text",
+        "InlineTextBox 'The players all played at once without waiting'",
+        "LayoutBlockFlow (floating) SPAN id='greenFloat'",
+        "LayoutText #text",
+        "InlineTextBox 'for turns,\n'",
+        "InlineTextBox 'quarrelling all the while, and fighting'",
+        "InlineTextBox 'for the hedgehogs; and in\n'",
+        "InlineTextBox 'a very short time '",
+        "LayoutText #text",
+        "InlineTextBox 'the'",
+        "InlineTextBox 'Queen'",
+        "LayoutText #text",
+        "InlineTextBox ' was in a furious passion, and went\n'",
+        "InlineTextBox 'stamping'",
+        "InlineTextBox 'about, and shouting \u2018Off with his head!\u2019 or \u2018Off with'",
+        "InlineTextBox 'her head!\u2019 about once in a minute.\n'",
+        "LayoutText #text",
+        "InlineTextBox 'Alice began to feel very uneasy: to be sure, she had not as\n'",
+        "InlineTextBox 'yet'",
+        "InlineTextBox 'had any dispute with the Queen, but she knew that it might'",
+        "InlineTextBox 'happen any minute, \u2018and then,\u2019 thought she, \u2018what would'",
+        "InlineTextBox 'become of\n'",
+        "InlineTextBox 'me? They\u2019re dreadfully fond of beheading people'",
+        "InlineTextBox 'here; the great\n'",
+        "InlineTextBox 'wonder is, that there\u2018s any one left alive!\u2019'"
       ]
     }
   ]
 }