Use [LegacyWindowAlias] for SVG* and WebKitCSSMatrix (#167)

See whatwg/webidl#362

Tests: web-platform-tests/wpt#5991

Author: zcorpan

geometry/Overview.bs

@@ -89,7 +89,8 @@ interface DOMPointReadOnly {
 [Constructor(optional unrestricted double x = 0, optional unrestricted double y = 0,
              optional unrestricted double z = 0, optional unrestricted double w = 1),
  Exposed=(Window,Worker),
- Serializable]
+ Serializable,
+ LegacyWindowAlias=SVGPoint]
 interface DOMPoint : DOMPointReadOnly {
     [NewObject] static DOMPoint fromPoint(optional DOMPointInit other);
 
@@ -213,9 +214,8 @@ and returns a new {{DOMPoint}} object.
  the attribute values <code>x: 20</code> and <code>y: 18</code>.
 </div>
 
-<p>For historical reasons, {{Window}} objects must also have a writable, configurable,
-non-enumerable property named <dfn dfn-type=interface><code>SVGPoint</code></dfn> whose value is the
-{{DOMPoint}} interface object.
+<p>For historical reasons, the {{DOMPoint}} interface has the legacy window alias <dfn
+dfn-type=interface><code>SVGPoint</code></dfn>.
 
 
 <h2 id=DOMRect>The DOMRect interfaces</h2>
@@ -271,7 +271,8 @@ interface DOMRectReadOnly {
 [Constructor(optional unrestricted double x = 0, optional unrestricted double y = 0,
              optional unrestricted double width = 0, optional unrestricted double height = 0),
  Exposed=(Window,Worker),
- Serializable]
+ Serializable,
+ LegacyWindowAlias=SVGRect]
 interface DOMRect : DOMRectReadOnly {
     [NewObject] static DOMRect fromRect(optional DOMRectInit other);
 
@@ -373,9 +374,8 @@ steps:
  coordinate</a>, <a for=rectangle>x coordinate</a> + <a for=rectangle>width dimension</a>).
 </div>
 
-<p>For historical reasons, {{Window}} objects must also have a writable, configurable,
-non-enumerable property named <dfn dfn-type=interface><code>SVGRect</code></dfn> whose value is the
-{{DOMRect}} interface object.
+<p>For historical reasons, the {{DOMRect}} interface has the legacy window alias <dfn
+dfn-type=interface><code>SVGRect</code></dfn>.
 
 
 <h2 id=DOMQuad>The DOMQuad interface</h2>
@@ -698,7 +698,8 @@ interface DOMMatrixReadOnly {
 
 [Constructor(optional (DOMString or sequence&lt;unrestricted double>) init),
  Exposed=(Window,Worker),
- Serializable]
+ Serializable,
+ LegacyWindowAlias=(SVGMatrix,WebKitCSSMatrix)]
 interface DOMMatrix : DOMMatrixReadOnly {
     [NewObject] static DOMMatrix fromMatrix(optional DOMMatrixInit other);
     [NewObject] static DOMMatrix fromFloat32Array(Float32Array array32);
@@ -808,10 +809,9 @@ prose.
 <p>The {{DOMMatrix}} and {{DOMMatrixReadOnly}} interfaces replace the <code>SVGMatrix</code>
 interface from SVG. [[SVG11]]
 
-<p>For historical reasons, {{Window}} objects must also have writable, configurable, non-enumerable
-properties named <dfn dfn-type=interface><code>SVGMatrix</code></dfn> and <dfn
-dfn-type=interface><code>WebKitCSSMatrix</code></dfn> whose value is the {{DOMMatrix}} interface
-object.
+<p>For historical reasons, the {{DOMMatrix}} interface has the legacy window aliases <dfn
+dfn-type=interface><code>SVGMatrix</code></dfn> and <dfn
+dfn-type=interface><code>WebKitCSSMatrix</code></dfn>.
 
 
 <h3 id=dommatrixinit-dictionary>DOMMatrixInit dictionary</h3>