Support subpixel values for text-shadow and box-shadow

LayoutTests/fast/sub-pixel/shadows-hidpi-expected.txt

Index: LayoutTests/fast/sub-pixel/shadows-hidpi-expected.txt
diff --git a/LayoutTests/fast/sub-pixel/shadows-hidpi-expected.txt b/LayoutTests/fast/sub-pixel/shadows-hidpi-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..15de5fb649c8eed2c08502bda14227e72ec71ef3
--- /dev/null
+++ b/LayoutTests/fast/sub-pixel/shadows-hidpi-expected.txt
@@ -0,0 +1,20 @@
+layer at (0,0) size 800x600
+  RenderView at (0,0) size 800x600
+layer at (0,0) size 800x58
+  RenderBlock {HTML} at (0,0) size 800x58
+    RenderBody {BODY} at (8,8) size 784x42
+      RenderBlock {DIV} at (0,0) size 784x10
+        RenderText {#text} at (0,0) size 30x10
+          text run at (0,0) width 30: "XXX"
+      RenderBlock (anonymous) at (0,10) size 784x32
+        RenderBR {BR} at (0,0) size 0x10
+        RenderBR {BR} at (0,10) size 0x10
+        RenderBlock {DIV} at (0,20) size 32x12 [border: (1px solid #000000)]
+          RenderText {#text} at (1,1) size 30x10
+            text run at (1,1) width 30: "XXX"
+        RenderText {#text} at (32,21) size 10x10
+          text run at (32,21) width 10: " "
+        RenderBlock {DIV} at (42,20) size 32x12 [border: (1px solid #000000)]
+          RenderText {#text} at (1,1) size 30x10
+            text run at (1,1) width 30: "XXX"
+        RenderText {#text} at (0,0) size 0x0