Preserve fractional scroll offset for JS scrolling API

Source/platform/geometry/DoubleSize.h

Index: Source/platform/geometry/DoubleSize.h
diff --git a/Source/platform/geometry/DoubleSize.h b/Source/platform/geometry/DoubleSize.h
index cb68834563d26ce5a6e9288cbc3d6710b0595dec..0d96115ba5e31a9a5b02fa431b99c33df0d8d3d8 100644
--- a/Source/platform/geometry/DoubleSize.h
+++ b/Source/platform/geometry/DoubleSize.h
@@ -15,6 +15,7 @@ class PLATFORM_EXPORT DoubleSize {
 public:
     DoubleSize() : m_width(0), m_height(0) { }
     DoubleSize(double width, double height) : m_width(width), m_height(height) { }
+    DoubleSize(const IntSize& p) : m_width(p.width()), m_height(p.height()) { }
 
     double width() const { return m_width; }
     double height() const { return m_height; }
@@ -37,6 +38,21 @@ inline DoubleSize& operator+=(DoubleSize& a, const DoubleSize& b)
     return a;
 }
 
+inline DoubleSize operator+(const DoubleSize& a, const IntSize& b)

[Rick Byers, 2014/10/02 21:44:06]

are these still necessary if you have the implicit conversion operator above?  I
don't see any such methods on FloatSize.

[Yufeng Shen (Slow to review), 2014/10/02 23:34:35]

removed.

+{
+    return DoubleSize(a.width() + b.width(), a.height() + b.height());
+}
+
+inline DoubleSize operator+(const IntSize& a, const DoubleSize& b)
+{
+    return DoubleSize(a.width() + b.width(), a.height() + b.height());
+}
+
+inline DoubleSize operator+(const DoubleSize& a, const DoubleSize& b)
+{
+    return DoubleSize(a.width() + b.width(), a.height() + b.height());
+}
+
 inline DoubleSize operator-(const DoubleSize& a, const DoubleSize& b)
 {
     return DoubleSize(a.width() - b.width(), a.height() - b.height());
@@ -47,6 +63,11 @@ inline bool operator==(const DoubleSize& a, const DoubleSize& b)
     return a.width() == b.width() && a.height() == b.height();
 }
 
+inline bool operator!=(const DoubleSize& a, const DoubleSize& b)
+{
+    return a.width() != b.width() || a.height() != b.height();
+}
+
 inline IntSize flooredIntSize(const DoubleSize& p)
 {
     return IntSize(clampToInteger(floor(p.width())), clampToInteger(floor(p.height())));