Implement select element list box with shadow DOM.

LayoutTests/platform/chromium-linux/fast/forms/listbox-hit-test-zoomed-expected.txt

Index: LayoutTests/platform/chromium-linux/fast/forms/listbox-hit-test-zoomed-expected.txt
diff --git a/LayoutTests/platform/chromium-linux/fast/forms/listbox-hit-test-zoomed-expected.txt b/LayoutTests/platform/chromium-linux/fast/forms/listbox-hit-test-zoomed-expected.txt
index 1dfab6a1f493134dc8e4e1fdc6aadc5841a37173..f52bee86657f18be3961ffe6a26327b317767409 100644
--- a/LayoutTests/platform/chromium-linux/fast/forms/listbox-hit-test-zoomed-expected.txt
+++ b/LayoutTests/platform/chromium-linux/fast/forms/listbox-hit-test-zoomed-expected.txt
@@ -4,7 +4,6 @@ layer at (0,0) size 800x585
   RenderBlock {HTML} at (0,0) size 800x585
     RenderBody {BODY} at (9,9) size 782x561
       RenderBlock (anonymous) at (0,0) size 781x162
-        RenderListBox {SELECT} at (2,0) size 138x162 [bgcolor=#FFFFFF] [border: (12px solid #000000)]
         RenderText {#text} at (0,0) size 0x0
       RenderBlock {DIV} at (0,162) size 781x118
         RenderBlock (anonymous) at (0,0) size 781x66
@@ -23,3 +22,56 @@ layer at (0,0) size 800x585
           RenderBR {BR} at (0,0) size 0x0
           RenderText {#text} at (0,18) size 1130x18
             text run at (0,18) width 1130: "     Actual: false,false,false,false,false,true,false,false,false,false,false,false,false,false,false,false,false"
+layer at (12,10) size 139x162 backgroundClip at (12,10) size 138x162 clip at (24,22) size 99x138 scrollY 7 scrollHeight 366
+  RenderListBox {SELECT} at (2,0) size 139x162 [bgcolor=#FFFFFF] [border: (12px solid #000000)]
+    RenderBlock {OPTION} at (24,24) size 76x21
+      RenderText {#text} at (2,0) size 26x18
+        text run at (2,0) width 26: "one"
+    RenderBlock {OPTION} at (24,44) size 76x21
+      RenderText {#text} at (2,0) size 24x18
+        text run at (2,0) width 24: "two"
+    RenderBlock {OPTION} at (24,64) size 76x21
+      RenderText {#text} at (2,0) size 35x18
+        text run at (2,0) width 35: "three"
+    RenderBlock {OPTION} at (24,84) size 76x21
+      RenderText {#text} at (2,0) size 26x18
+        text run at (2,0) width 26: "four"
+    RenderBlock {OPTION} at (24,104) size 76x21
+      RenderText {#text} at (2,0) size 24x18
+        text run at (2,0) width 24: "five"
+    RenderBlock {OPTION} at (24,124) size 76x22 [bgcolor=#1E90FF]
+      RenderText {#text} at (2,0) size 19x18
+        text run at (2,0) width 19: "six"
+    RenderBlock {OPTION} at (24,145) size 76x21
+      RenderText {#text} at (2,0) size 41x18
+        text run at (2,0) width 41: "seven"
+    RenderBlock {OPTION} at (24,165) size 76x21
+      RenderText {#text} at (2,0) size 34x18
+        text run at (2,0) width 34: "eight"
+    RenderBlock {OPTION} at (24,185) size 76x21
+      RenderText {#text} at (2,0) size 29x18
+        text run at (2,0) width 29: "nine"
+    RenderBlock {OPTION} at (24,205) size 76x21
+      RenderText {#text} at (2,0) size 21x18
+        text run at (2,0) width 21: "ten"
+    RenderBlock {OPTION} at (24,225) size 76x22
+      RenderText {#text} at (2,0) size 45x18
+        text run at (2,0) width 45: "eleven"
+    RenderBlock {OPTION} at (24,246) size 76x21
+      RenderText {#text} at (2,0) size 43x18
+        text run at (2,0) width 43: "twelve"
+    RenderBlock {OPTION} at (24,266) size 76x21
+      RenderText {#text} at (2,0) size 51x18
+        text run at (2,0) width 51: "thirteen"
+    RenderBlock {OPTION} at (24,286) size 76x21
+      RenderText {#text} at (2,0) size 56x18
+        text run at (2,0) width 56: "fourteen"
+    RenderBlock {OPTION} at (24,306) size 76x21
+      RenderText {#text} at (2,0) size 42x18
+        text run at (2,0) width 42: "fifteen"
+    RenderBlock {OPTION} at (24,326) size 76x21
+      RenderText {#text} at (2,0) size 49x18
+        text run at (2,0) width 49: "sixteen"
+    RenderBlock {OPTION} at (24,347) size 76x19
+      RenderText {#text} at (2,0) size 71x18
+        text run at (2,0) width 71: "seventeen"