Perspective property should only allow positive lengths

LayoutTests/transforms/webkit-perspective-parsing.html

Index: LayoutTests/transforms/webkit-perspective-parsing.html
diff --git a/LayoutTests/transforms/perspective-parsing.html b/LayoutTests/transforms/webkit-perspective-parsing.html
similarity index 62%
copy from LayoutTests/transforms/perspective-parsing.html
copy to LayoutTests/transforms/webkit-perspective-parsing.html
index 221a8a985a40f6337553006f8ac21b3134d3b066..e3df1ffa4c66ceebdfcc958d6bec1ea76ffd56d3 100644
--- a/LayoutTests/transforms/perspective-parsing.html
+++ b/LayoutTests/transforms/webkit-perspective-parsing.html
@@ -4,7 +4,7 @@
 <div id="target"></div>
 <script src="resources/parsing-test-helper.js"></script>
 <script>
-expect = expect.bind(this, 'perspective', 'perspective');
+expect = expect.bind(this, '-webkit-perspective', 'webkitPerspective');
 
 expect('initial').parsesAs('initial').isComputedTo('none');
 expect('inherit').parsesAs('inherit');
@@ -14,7 +14,14 @@ expect('1px').parsesAs('1px').isComputedTo('1px');
 
 expect('0').isInvalid();
 expect('0px').isInvalid();
-expect('5').isInvalid();
+expect('5').parsesAs('5');
 expect('-1px').isInvalid();
 expect('50%').isInvalid();
+expect('calc(-1px)').isInvalid();
+expect('calc(0px)').isInvalid();
+expect('calc(1px)').parsesAs('calc(1px)');
+expect('calc(-1)').isInvalid();
+expect('calc(0)').isInvalid();
+expect('calc(1)').parsesAs('calc(1)');
+</script>
 </script>