Unprefix the @viewport rule of CSS Device Adaptation spec

LayoutTests/css3/device-adapt/opera/constrain-018.html

Index: LayoutTests/css3/device-adapt/opera/constrain-018.html
diff --git a/LayoutTests/css3/device-adapt/opera/constrain-018.html b/LayoutTests/css3/device-adapt/opera/constrain-018.html
index 77fbd4bbf23d9a60a307c2c367af46db69fbd183..6d706e57bf3b1462114f987c8d6bd19f701c6850 100644
--- a/LayoutTests/css3/device-adapt/opera/constrain-018.html
+++ b/LayoutTests/css3/device-adapt/opera/constrain-018.html
@@ -14,7 +14,7 @@
    html, body, #test { width: 100%; height: 100%; }
    #log { padding: 1em; display: none; }
    /* Reset viewport values to initial values to ignore UA stylesheet. */
-   @-webkit-viewport {
+   @viewport {
     width: auto;
     height: auto;
     zoom: auto;
@@ -27,7 +27,7 @@
   </style>
   <style type="text/css">
    /* CSS for the test below. */
-   @-webkit-viewport { width: 0em }
+   @viewport { width: 0em }
    /* Set root element font-size to something different from the initial
       font-size to make sure 'rem' and 'em' for @viewport is based on the
       initial font-size, not the root element font-size. */