WebKitCSSMatrix compat: optional arguments

Make all arguments optional for DOMMatrix/DOMMatrixReadOnly methods,
except for setMatrixValue() which throws in WebKit anyway (because
"undefined" fails to parse). I made everything optional to be
consistent; making the minimal set of arguments optional would
be self-inconsistent and confusing (e.g. skewX vs. skewXSelf).

Part of whatwg/compat#19

Author: zcorpan

geometry/Overview.bs

@@ -438,30 +438,30 @@ interface DOMMatrixReadOnly {
     readonly attribute boolean isIdentity;
 
     // Immutable transform methods
-    DOMMatrix translate(unrestricted double tx,
-                        unrestricted double ty,
+    DOMMatrix translate(optional unrestricted double tx = 0,
+                        optional unrestricted double ty = 0,
                         optional unrestricted double tz = 0);
     DOMMatrix scale(optional unrestricted double scaleX = 1,
                     optional unrestricted double scaleY,
                     optional unrestricted double scaleZ = 1,
                     optional unrestricted double originX = 0,
                     optional unrestricted double originY = 0,
                     optional unrestricted double originZ = 0);
-    DOMMatrix scale3d(unrestricted double scale,
+    DOMMatrix scale3d(optional unrestricted double scale = 1,
                       optional unrestricted double originX = 0,
                       optional unrestricted double originY = 0,
                       optional unrestricted double originZ = 0);
     DOMMatrix rotate(optional unrestricted double rotX = 0,
                      optional unrestricted double rotY,
                      optional unrestricted double rotZ);
-    DOMMatrix rotateFromVector(unrestricted double x,
-                               unrestricted double y);
-    DOMMatrix rotateAxisAngle(unrestricted double x,
-                              unrestricted double y,
-                              unrestricted double z,
-                              unrestricted double angle);
-    DOMMatrix skewX(unrestricted double sx);
-    DOMMatrix skewY(unrestricted double sy);
+    DOMMatrix rotateFromVector(optional unrestricted double x = 0,
+                               optional unrestricted double y = 0);
+    DOMMatrix rotateAxisAngle(optional unrestricted double x = 0,
+                              optional unrestricted double y = 0,
+                              optional unrestricted double z = 0,
+                              optional unrestricted double angle = 0);
+    DOMMatrix skewX(optional unrestricted double sx = 0);
+    DOMMatrix skewY(optional unrestricted double sy = 0);
     DOMMatrix multiply(optional DOMMatrixInit other);
     DOMMatrix flipX();
     DOMMatrix flipY();
@@ -510,30 +510,30 @@ interface DOMMatrix : DOMMatrixReadOnly {
     // Mutable transform methods
     DOMMatrix multiplySelf(optional DOMMatrixInit other);
     DOMMatrix preMultiplySelf(optional DOMMatrixInit other);
-    DOMMatrix translateSelf(unrestricted double tx,
-                     unrestricted double ty,
-                     optional unrestricted double tz = 0);
+    DOMMatrix translateSelf(optional unrestricted double tx = 0,
+                            optional unrestricted double ty = 0,
+                            optional unrestricted double tz = 0);
     DOMMatrix scaleSelf(optional unrestricted double scaleX = 1,
                         optional unrestricted double scaleY,
                         optional unrestricted double scaleZ = 1,
                         optional unrestricted double originX = 0,
                         optional unrestricted double originY = 0,
                         optional unrestricted double originZ = 0);
-    DOMMatrix scale3dSelf(unrestricted double scale,
-                   optional unrestricted double originX = 0,
-                   optional unrestricted double originY = 0,
-                   optional unrestricted double originZ = 0);
+    DOMMatrix scale3dSelf(optional unrestricted double scale = 1,
+                          optional unrestricted double originX = 0,
+                          optional unrestricted double originY = 0,
+                          optional unrestricted double originZ = 0);
     DOMMatrix rotateSelf(optional unrestricted double rotX = 0,
                          optional unrestricted double rotY,
                          optional unrestricted double rotZ);
-    DOMMatrix rotateFromVectorSelf(unrestricted double x,
-                            unrestricted double y);
-    DOMMatrix rotateAxisAngleSelf(unrestricted double x,
-                           unrestricted double y,
-                           unrestricted double z,
-                           unrestricted double angle);
-    DOMMatrix skewXSelf(unrestricted double sx);
-    DOMMatrix skewYSelf(unrestricted double sy);
+    DOMMatrix rotateFromVectorSelf(optional unrestricted double x = 0,
+                                   optional unrestricted double y = 0);
+    DOMMatrix rotateAxisAngleSelf(optional unrestricted double x = 0,
+                                  optional unrestricted double y = 0,
+                                  optional unrestricted double z = 0,
+                                  optional unrestricted double angle = 0);
+    DOMMatrix skewXSelf(optional unrestricted double sx = 0);
+    DOMMatrix skewYSelf(optional unrestricted double sy = 0);
     DOMMatrix invertSelf();
 
     DOMMatrix setMatrixValue(DOMString transformList);