Adding fromPoint to DOMPoint and DOMPointReadOnly interfaces following spec.

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

Index: third_party/WebKit/Source/core/dom/DOMPointReadOnly.cpp
diff --git a/third_party/WebKit/Source/core/dom/DOMPointReadOnly.cpp b/third_party/WebKit/Source/core/dom/DOMPointReadOnly.cpp
index e62791e37598756a2fffdb02bcf8ad953ebd1ee7..af4d080b1f435ca2f2a03e96d5fc9a08b5160e45 100644
--- a/third_party/WebKit/Source/core/dom/DOMPointReadOnly.cpp
+++ b/third_party/WebKit/Source/core/dom/DOMPointReadOnly.cpp
@@ -4,6 +4,8 @@
 
 #include "core/dom/DOMPointReadOnly.h"
 
+#include "core/dom/DOMPointInit.h"
+
 namespace blink {
 
 DOMPointReadOnly* DOMPointReadOnly::create(double x,
@@ -13,6 +15,10 @@ DOMPointReadOnly* DOMPointReadOnly::create(double x,
   return new DOMPointReadOnly(x, y, z, w);
 }
 
+DOMPointReadOnly* DOMPointReadOnly::fromPoint(const DOMPointInit& other) {
+  return new DOMPointReadOnly(other.x(), other.y(), other.z(), other.w());
+}
+
 DOMPointReadOnly::DOMPointReadOnly(double x, double y, double z, double w)
     : m_x(x), m_y(y), m_z(z), m_w(w) {}