Enable experimental support for sub-pixel font scaling

LayoutTests/fast/text/sub-pixel/resources/text-scaling.css

Index: LayoutTests/fast/text/sub-pixel/resources/text-scaling.css
diff --git a/LayoutTests/fast/text/sub-pixel/resources/text-scaling.css b/LayoutTests/fast/text/sub-pixel/resources/text-scaling.css
new file mode 100644
index 0000000000000000000000000000000000000000..015b50da9005dea9dc78163c1151d121908f3784
--- /dev/null
+++ b/LayoutTests/fast/text/sub-pixel/resources/text-scaling.css
@@ -0,0 +1,39 @@
+section {
+    margin: 0 0 1em 0;
+    display: inline-block;
+}
+
+section > h1 {
+    font-weight: bold;
+    margin: 0;
+}
+
+section > p {
+    margin: 0.25em 0;
+}
+
+section > div > div {
+    font: normal 10px Helvetica;
+    white-space: nowrap;
+}
+
+section > div > div.header {
+    border: solid black;
+    border-width: 0 0 1px 0;
+}
+
+section > div > div > div {
+    display: inline-block;
+    width: 12ex;
+    text-align: right;
+    padding: 0 1ex 0 0;
+}
+
+.reference {
+    background: infobackground;
+}
+
+.size-fail > .results {
+    color: red;
+    font-weight: bold;
+}