Implement select listbox using shadow DOM

LayoutTests/platform/mac/fast/forms/select-multiple-rtl-expected.txt

Index: LayoutTests/platform/mac/fast/forms/select-multiple-rtl-expected.txt
diff --git a/LayoutTests/platform/mac/fast/forms/select-multiple-rtl-expected.txt b/LayoutTests/platform/mac/fast/forms/select-multiple-rtl-expected.txt
index eb3ad05c7c8e0154f9d9f8693e8641cc6ec57215..61644a0313983480772eaca01302cd56e3da92e6 100644
--- a/LayoutTests/platform/mac/fast/forms/select-multiple-rtl-expected.txt
+++ b/LayoutTests/platform/mac/fast/forms/select-multiple-rtl-expected.txt
@@ -1,13 +1,29 @@
 layer at (0,0) size 800x600
   RenderView at (0,0) size 800x600
-layer at (0,0) size 800x119
-  RenderBlock {HTML} at (0,0) size 800x119
-    RenderBody {BODY} at (8,8) size 784x103
+layer at (0,0) size 800x120
+  RenderBlock {HTML} at (0,0) size 800x120
+    RenderBody {BODY} at (8,8) size 784x104
       RenderBlock (anonymous) at (0,0) size 784x18
         RenderInline {SPAN} at (0,0) size 633x18
           RenderText {#text} at (0,0) size 633x18
             text run at (0,0) width 633: "Test for crbug.com/335285: On OS Mac, Options of a multiple select are shifted right in RTL mode."
         RenderText {#text} at (0,0) size 0x0
-      RenderBlock {DIV} at (0,18) size 784x85
-        RenderListBox {SELECT} at (584,0) size 200x85 [bgcolor=#FFFFFF] [border: (1px inset #808080)]
+      RenderBlock {DIV} at (0,18) size 784x86
         RenderText {#text} at (0,0) size 0x0
+layer at (592,26) size 200x86 clip at (604,27) size 187x84
+  RenderListBox {SELECT} at (584,0) size 200x86 [bgcolor=#F8F8F8] [border: (1px inset #999999)]
+    RenderBlock {OPTION} at (12,1) size 187x14
+      RenderText {#text} at (151,0) size 34x13
+        text run at (151,0) width 34: "Test 1"
+    RenderBlock {OPTION} at (12,15) size 187x14
+      RenderText {#text} at (151,0) size 34x13
+        text run at (151,0) width 34: "Test 2"
+    RenderBlock {OPTION} at (12,29) size 187x14
+      RenderText {#text} at (151,0) size 34x13
+        text run at (151,0) width 34: "Test 3"
+    RenderBlock {OPTION} at (12,43) size 187x14
+      RenderText {#text} at (151,0) size 34x13
+        text run at (151,0) width 34: "Test 4"
+    RenderBlock {OPTION} at (12,57) size 187x14
+      RenderText {#text} at (151,0) size 34x13
+        text run at (151,0) width 34: "Test 5"