gistfile1.txt

diff --git a/geometry/Overview.bs b/geometry/Overview.bs
index 4a4c40a..8c2ca9f 100644
--- a/geometry/Overview.bs
+++ b/geometry/Overview.bs
@@ -58,7 +58,7 @@ interface DOMPointReadOnly {
     readonly attribute unrestricted double z;
     readonly attribute unrestricted double w;
 
-    DOMPoint matrixTransform(DOMMatrixReadOnly matrix);
+    DOMPoint matrixTransform(optional DOMMatrixInit matrix);
 };
 
 [Constructor(optional DOMPointInit point),
@@ -490,7 +490,7 @@ interface DOMMatrixReadOnly {
                               unrestricted double angle);
     DOMMatrix skewX(unrestricted double sx);
     DOMMatrix skewY(unrestricted double sy);
-    DOMMatrix multiply(DOMMatrix other);
+    DOMMatrix multiply(optional DOMMatrixInit other);
     DOMMatrix flipX();
     DOMMatrix flipY();
     DOMMatrix inverse();
@@ -501,9 +501,8 @@ interface DOMMatrixReadOnly {
                         stringifier;
 };
 
-[Constructor,
- Constructor(DOMString transformList),
- Constructor(DOMMatrixReadOnly other),
+[Constructor(DOMString transformList),
+ Constructor(optional DOMMatrixInit other),
  Constructor(Float32Array array32),
  Constructor(Float64Array array64),
  Constructor(sequence<unrestricted double> numberSequence),
@@ -535,8 +534,8 @@ interface DOMMatrix : DOMMatrixReadOnly {
     inherit attribute unrestricted double m44;
 
     // Mutable transform methods
-    DOMMatrix multiplySelf(DOMMatrix other);
-    DOMMatrix preMultiplySelf(DOMMatrix other);
+    DOMMatrix multiplySelf(optional DOMMatrixInit other);
+    DOMMatrix preMultiplySelf(optional DOMMatrixInit other);
     DOMMatrix translateSelf(unrestricted double tx,
                      unrestricted double ty,
                      optional unrestricted double tz = 0);
@@ -568,6 +567,32 @@ interface DOMMatrix : DOMMatrixReadOnly {
 
     DOMMatrix setMatrixValue(DOMString transformList);
 };
+
+dictionary DOMMatrixInit {
+    unrestricted double a;
+    unrestricted double b;
+    unrestricted double c;
+    unrestricted double d;
+    unrestricted double e;
+    unrestricted double f;
+    unrestricted double m11;
+    unrestricted double m12;
+    unrestricted double m13 = 0;
+    unrestricted double m14 = 0;
+    unrestricted double m21;
+    unrestricted double m22;
+    unrestricted double m23 = 0;
+    unrestricted double m24 = 0;
+    unrestricted double m31 = 0;
+    unrestricted double m32 = 0;
+    unrestricted double m33 = 1;
+    unrestricted double m34 = 0;
+    unrestricted double m41;
+    unrestricted double m42;
+    unrestricted double m43 = 0;
+    unrestricted double m44 = 1;
+    boolean is2D;
+};
 </pre>
 
 The following algorithms assume that <a interface>DOMMatrixReadOnly</a> objects have the internal member variables <dfn dfn-for=matrix>m11 element</dfn>, <dfn dfn-for=matrix>m12 element</dfn>, <dfn dfn-for=matrix>m13 element</dfn>, <dfn dfn-for=matrix>m14 element</dfn>, <dfn dfn-for=matrix>m21 element</dfn>, <dfn dfn-for=matrix>m22 element</dfn>, <dfn dfn-for=matrix>m23 element</dfn>, <dfn dfn-for=matrix>m24 element</dfn>, <dfn dfn-for=matrix>m31 element</dfn>, <dfn dfn-for=matrix>m32 element</dfn>, <dfn dfn-for=matrix>m33 element</dfn>, <dfn dfn-for=matrix>m34 element</dfn>, <dfn dfn-for=matrix>m41 element</dfn>, <dfn dfn-for=matrix>m42 element</dfn>, <dfn dfn-for=matrix>m43 element</dfn>, <dfn dfn-for=matrix>m44 element</dfn> and <a>is2D</a>. <a interface>DOMMatrixReadOnly</a> as well as the inheriting interface <a interface>DOMMatrix</a> must be able to access and set the value of these variables.
@@ -580,6 +605,55 @@ The <a interface>DOMMatrix</a> and <a interface>DOMMatrixReadOnly</a> interfaces
 
 For historical reasons, Window objects must also have a writable, configurable, non-enumerable property named <dfn dfn-type=interface>SVGMatrix</dfn> whose value is the <a interface>DOMMatrix</a> interface object.
 
+<h3 id='dommatrixinit-dictionary'>DOMMatrixInit dictionary</h3>
+
+To <dfn>validate and fixup</dfn> a {{DOMMatrixInit}} dictionary <var>dict</var>, run the following steps:
+
+<ol>
+  <li>If if at least one of the following conditions are true for <var>dict</var>, throw a <code>TypeError</code> exception and abort these steps.
+    <ul>
+      <li>{{DOMMatrixInit/a}} and {{DOMMatrixInit/m11}} are both present and their values are not the same.
+      <li>{{DOMMatrixInit/b}} and {{DOMMatrixInit/m12}} are both present and their values are not the same.
+      <li>{{DOMMatrixInit/c}} and {{DOMMatrixInit/m21}} are both present and their values are not the same.
+      <li>{{DOMMatrixInit/d}} and {{DOMMatrixInit/m22}} are both present and their values are not the same.
+      <li>{{DOMMatrixInit/e}} and {{DOMMatrixInit/m41}} are both present and their values are not the same.
+      <li>{{DOMMatrixInit/f}} and {{DOMMatrixInit/m42}} are both present and their values are not the same.
+      <li>{{DOMMatrixInit/is2D}} is <code>true</code> and at least one of
+      {{DOMMatrixInit/m31}}, {{DOMMatrixInit/m32}}, {{DOMMatrixInit/m13}}, {{DOMMatrixInit/m23}},
+      {{DOMMatrixInit/m43}}, {{DOMMatrixInit/m14}}, {{DOMMatrixInit/m24}}, {{DOMMatrixInit/m34}}
+      are present with a value other than ''0'',
+      or at least one of {{DOMMatrixInit/m33}}, {{DOMMatrixInit/m44}}
+      are present with a value other than ''1''.
+    </ul>
+  <li><a>Set the dictionary members</a> {{DOMMatrixInit/a}} and {{DOMMatrixInit/m11}} with fallback value ''1''.
+  <li><a>Set the dictionary members</a> {{DOMMatrixInit/b}} and {{DOMMatrixInit/m12}} with fallback value ''0''.
+  <li><a>Set the dictionary members</a> {{DOMMatrixInit/c}} and {{DOMMatrixInit/m21}} with fallback value ''0''.
+  <li><a>Set the dictionary members</a> {{DOMMatrixInit/d}} and {{DOMMatrixInit/m22}} with fallback value ''1''.
+  <li><a>Set the dictionary members</a> {{DOMMatrixInit/e}} and {{DOMMatrixInit/m41}} with fallback value ''0''.
+  <li><a>Set the dictionary members</a> {{DOMMatrixInit/f}} and {{DOMMatrixInit/m42}} with fallback value ''0''.
+  <li>If {{DOMMatrixInit/is2D}} is not present and at least one of
+  {{DOMMatrixInit/m31}}, {{DOMMatrixInit/m32}}, {{DOMMatrixInit/m13}}, {{DOMMatrixInit/m23}},
+  {{DOMMatrixInit/m43}}, {{DOMMatrixInit/m14}}, {{DOMMatrixInit/m24}}, {{DOMMatrixInit/m34}}
+  are present with a value other than ''0'',
+  or at least one of {{DOMMatrixInit/m33}}, {{DOMMatrixInit/m44}}
+  are present with a value other than ''1'',
+  set {{DOMMatrixInit/is2D}} to <code>false</code>.
+  <li>If {{DOMMatrixInit/is2D}} is still not present, set it to <code>true</code>.
+</ol>
+
+For the purpose of the algorithm above, two WebIDL unrestricted double values <var>a</var> and <var>b</var>
+are the same if they have identical IEEE 754 double-precision bit patterns.
+
+Note: This means that two ''NaN'' values are the same.
+
+To <dfn>set the dictionary members</dfn> <var>a</var> and <var>b</var> of a {{DOMMatrixInit}} dictionary, with a fallback value <var>fallback</var>, run the following steps:
+
+<ol>
+  <li>If <var>a</var> is present and <var>b</var> is not present, set the <var>b</var> dictionary member to the value of <var>a</var>.
+  <li>Otherwise, if <var>b</var> is present and <var>a</var> is not present, set the <var>a</var> dictionary member to the value of <var>b</var>.
+  <li>Otherwise, set <var>a</var> and <var>b</var> dictionary members to <var>fallback</var>.
+</ol>
+
 <h3 id='dommatrixreadonly-constructors'>DOMMatrixReadOnly constructor</h3>
 
 The <dfn dfn-type=constructor dfn-for=DOMMatrixReadOnly><code>DOMMatrixReadOnly(sequence&lt;unrestricted double> <var>numberSequence</var>)</code></dfn> constructor, when invoked, must run the following steps: