[GeometryInterface] add transformPoint(point) function.

third_party/WebKit/Source/core/dom/DOMMatrixReadOnly.cpp

Index: third_party/WebKit/Source/core/dom/DOMMatrixReadOnly.cpp
diff --git a/third_party/WebKit/Source/core/dom/DOMMatrixReadOnly.cpp b/third_party/WebKit/Source/core/dom/DOMMatrixReadOnly.cpp
index 7cf081eecea7c77028b720eef25e99c27d7ed05e..300bec43cfeb740d23140f6d2904bbd00ad2369b 100644
--- a/third_party/WebKit/Source/core/dom/DOMMatrixReadOnly.cpp
+++ b/third_party/WebKit/Source/core/dom/DOMMatrixReadOnly.cpp
@@ -4,6 +4,8 @@
 
 #include "core/dom/DOMMatrix.h"
 #include "core/dom/DOMMatrixInit.h"
+#include "core/dom/DOMPoint.h"
+#include "core/dom/DOMPointInit.h"
 
 namespace blink {
 namespace {
@@ -210,6 +212,18 @@ DOMMatrix* DOMMatrixReadOnly::inverse() {
   return DOMMatrix::create(this)->invertSelf();
 }
 
+DOMPoint* DOMMatrixReadOnly::transformPoint(DOMPointInit& point) {

[zino, 2016/10/17 15:44:44]

The spec says that "Even if is2D of the current matrix returns true, a 4x4
matrix multiplication will be performed if the z attribute of point is not 0 or
the w attribute of point is not 1."

In other words, we can optimize this as follows:

if (is2D() && point.z() == 0 && point.w() == 1) {
  double x = point.x * m11 + point.y * m12 + m41;
  double y = point.x * m12 + point.y * m22 + m42;
  return DOMPoint::create(x, y, 0, 1);
}

Also, please add some tests for this.

[Hwanseung Lee, 2016/10/17 23:47:30]

Done.

+  double x = point.x() * m11() + point.y() * m21() + point.z() * m31() +
+             point.w() * m41();
+  double y = point.x() * m12() + point.y() * m22() + point.z() * m32() +
+             point.w() * m42();
+  double z = point.x() * m13() + point.y() * m23() + point.z() * m33() +
+             point.w() * m43();
+  double w = point.x() * m14() + point.y() * m24() + point.z() * m34() +
+             point.w() * m44();
+  return DOMPoint::create(x, y, z, w);
+}
+
 DOMFloat32Array* DOMMatrixReadOnly::toFloat32Array() const {
   float array[] = {
       static_cast<float>(m_matrix->m11()), static_cast<float>(m_matrix->m12()),