Sync core/timing/ interfaces with their specs, or lack thereof

Source/core/timing/MemoryInfo.idl

Index: Source/core/timing/MemoryInfo.idl
diff --git a/Source/core/timing/MemoryInfo.idl b/Source/core/timing/MemoryInfo.idl
index 66119c5e132cfc146a25a83bfcabe5fd705bebe9..325406dd677b1c8f4cbb3d15bac57f697160a102 100644
--- a/Source/core/timing/MemoryInfo.idl
+++ b/Source/core/timing/MemoryInfo.idl
@@ -28,13 +28,14 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+// TODO(philipj): There is no spec for the Memory Info API, see blink-dev:
+// https://groups.google.com/a/chromium.org/d/msg/blink-dev/g5YRCGpC9vs/b4OJz71NmPwJ
+
 [
     GarbageCollected,
     NoInterfaceObject
 ] interface MemoryInfo {
-
-    readonly attribute unsigned long totalJSHeapSize;
-    readonly attribute unsigned long usedJSHeapSize;
-    readonly attribute unsigned long jsHeapSizeLimit;
-
+    [Measure] readonly attribute unsigned long totalJSHeapSize;
+    [Measure] readonly attribute unsigned long usedJSHeapSize;
+    [Measure] readonly attribute unsigned long jsHeapSizeLimit;
 };