Make HTMLCanvasElement::convertLogicalToDevice() clamp float to integer.

Source/core/html/HTMLCanvasElement.cpp

 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 388 matching lines @@
     if (!m_context || !m_context->is3d())
        return 0;
 
     WebGLRenderingContext* ctx = static_cast<WebGLRenderingContext*>(m_context.get());
 
     return ctx->paintRenderingResultsToImageData();
 }
 
 IntSize HTMLCanvasElement::convertLogicalToDevice(const IntSize& logicalSize) const
 {
-    float width = ceilf(logicalSize.width() * m_deviceScaleFactor);
-    float height = ceilf(logicalSize.height() * m_deviceScaleFactor);
-    return IntSize(width, height);
+    FloatSize deviceSize = logicalSize * m_deviceScaleFactor;
+    return expandedIntSize(deviceSize);
 }
 
 SecurityOrigin* HTMLCanvasElement::securityOrigin() const
 {
     return document().securityOrigin();
 }
 
 StyleResolver* HTMLCanvasElement::styleResolver()
 {
     return document().styleResolver();
@@ skipping 127 matching lines @@
     ASSERT(m_hasCreatedImageBuffer);
     IntSize unscaledSize = size();
     IntSize size = convertLogicalToDevice(unscaledSize);
     AffineTransform transform;
     if (size.width() && size.height())
         transform.scaleNonUniform(size.width() / unscaledSize.width(), size.height() / unscaledSize.height());
     return m_imageBuffer->baseTransform() * transform;
 }
 
 }