[cssom-view] Do nothing for width=0/height=0 in window.open()

See web-platform-tests/wpt#5390 (comment)

Author: zcorpan

cssom-view/Overview.bs

@@ -669,6 +669,8 @@ To <dfn export>set up browsing context features</dfn> for a browsing context <va
 
 1. Let <var>x</var> be null.
 1. Let <var>y</var> be null.
+1. Let <var>width</var> be null.
+1. Let <var>height</var> be null.
 1. If <var>tokenizedFeatures</var>["<a for="supported open() feature name">left</a>"]
     <a for=map>exists</a>:
     1. Set <var>x</var> to the result of invoking the <a>rules for parsing integers</a> on
@@ -691,28 +693,30 @@ To <dfn export>set up browsing context features</dfn> for a browsing context <va
         area</a>, measured in CSS pixels of <var>target</var>. The positive axis is downward.
 1. If <var>tokenizedFeatures</var>["<a for="supported open() feature name">width</a>"]
     <a for=map>exists</a>:
-    1. Set <var>x</var> to the result of invoking the <a>rules for parsing integers</a> on
+    1. Set <var>width</var> to the result of invoking the <a>rules for parsing integers</a> on
         <var>tokenizedFeatures</var>["<a for="supported open() feature name">width</a>"].
-    1. If <var>x</var> is an error, set <var>x</var> to 0.
-    1. Optionally, clamp <var>x</var> in a user-agent-defined manner so that the window does not get
-        too small or bigger than the <a>Web-exposed available screen area</a>.
-    1. Optionally, size <var>target</var>'s window by moving its right edge such that the distance
-        between the left and right edges of the viewport are <var>x</var> CSS pixels of
-        <var>target</var>.
-    1. Optionally, move <var>target</var>'s window in a user-agent-defined manner so that it does
-        not grow outside the <a>Web-exposed available screen area</a>.
+    1. If <var>width</var> is an error, set <var>width</var> to 0.
+    1. If <var>width</var> is not 0:
+        1. Optionally, clamp <var>width</var> in a user-agent-defined manner so that the window does
+            not get too small or bigger than the <a>Web-exposed available screen area</a>.
+        1. Optionally, size <var>target</var>'s window by moving its right edge such that the
+            distance between the left and right edges of the viewport are <var>width</var> CSS
+            pixels of <var>target</var>.
+        1. Optionally, move <var>target</var>'s window in a user-agent-defined manner so that it
+            does not grow outside the <a>Web-exposed available screen area</a>.
 1. If <var>tokenizedFeatures</var>["<a for="supported open() feature name">height</a>"]
     <a for=map>exists</a>:
-    1. Set <var>y</var> to the result of invoking the <a>rules for parsing integers</a> on
+    1. Set <var>height</var> to the result of invoking the <a>rules for parsing integers</a> on
         <var>tokenizedFeatures</var>["<a for="supported open() feature name">height</a>"].
-    1. If <var>y</var> is an error, set <var>y</var> to 0.
-    1. Optionally, clamp <var>y</var> in a user-agent-defined manner so that the window does not get
-        too small or bigger than the <a>Web-exposed available screen area</a>.
-    1. Optionally, size <var>target</var>'s window by moving its bottom edge such that the distance
-        between the top and bottom edges of the viewport are <var>y</var> CSS pixels of
-        <var>target</var>.
-    1. Optionally, move <var>target</var>'s window in a user-agent-defined manner so that it does
-        not grow outside the <a>Web-exposed available screen area</a>.
+    1. If <var>height</var> is an error, set <var>height</var> to 0.
+    1. If <var>height</var> is not 0:
+        1. Optionally, clamp <var>height</var> in a user-agent-defined manner so that the window
+            does not get too small or bigger than the <a>Web-exposed available screen area</a>.
+        1. Optionally, size <var>target</var>'s window by moving its bottom edge such that the
+            distance between the top and bottom edges of the viewport are <var>height</var> CSS
+            pixels of <var>target</var>.
+        1. Optionally, move <var>target</var>'s window in a user-agent-defined manner so that it
+            does not grow outside the <a>Web-exposed available screen area</a>.
 
 A <dfn export>supported <code>open()</code> feature name</dfn> is one of the following: