Font metrics, version 1

Source/core/html/TextMetrics.idl

Index: Source/core/html/TextMetrics.idl
diff --git a/Source/core/html/TextMetrics.idl b/Source/core/html/TextMetrics.idl
index fc37998bda6bd4ebfeada371b95b000fad153246..14f11483dd22c0169c1f564d399f1ab4f2d9e278 100644
--- a/Source/core/html/TextMetrics.idl
+++ b/Source/core/html/TextMetrics.idl
@@ -24,6 +24,20 @@
  */
 [
 ] interface TextMetrics {
+    // x-direction
     readonly attribute float width;
+    [RuntimeEnabled=ExperimentalCanvasFeatures] readonly attribute float actualBoundingBoxLeft;
+    [RuntimeEnabled=ExperimentalCanvasFeatures] readonly attribute float actualBoundingBoxRight;
+
+    // y-direction
+    [RuntimeEnabled=ExperimentalCanvasFeatures] readonly attribute float fontBoundingBoxAscent;
+    [RuntimeEnabled=ExperimentalCanvasFeatures] readonly attribute float fontBoundingBoxDescent;
+    [RuntimeEnabled=ExperimentalCanvasFeatures] readonly attribute float actualBoundingBoxAscent;
+    [RuntimeEnabled=ExperimentalCanvasFeatures] readonly attribute float actualBoundingBoxDescent;
+    [RuntimeEnabled=ExperimentalCanvasFeatures] readonly attribute float emHeightAscent;
+    [RuntimeEnabled=ExperimentalCanvasFeatures] readonly attribute float emHeightDescent;
+    [RuntimeEnabled=ExperimentalCanvasFeatures] readonly attribute float hangingBaseline;
+    [RuntimeEnabled=ExperimentalCanvasFeatures] readonly attribute float alphabeticBaseline;
+    [RuntimeEnabled=ExperimentalCanvasFeatures] readonly attribute float ideographicBaseline;
 };