CanvasRenderingContext2D should update the render tree to avoid stale computed style.

Source/core/html/canvas/CanvasRenderingContext2D.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008 Dirk Schulze <krit@webkit.org>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  * Copyright (C) 2012, 2013 Intel Corporation. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
@@ skipping 1932 matching lines @@
         return;
 
     // The parse succeeded.
     String newFontSafeCopy(newFont); // Create a string copy since newFont can be deleted inside realizeSaves.
     realizeSaves(0);
     modifiableState().m_unparsedFont = newFontSafeCopy;
 
     // Map the <canvas> font into the text style. If the font uses keywords like larger/smaller, these will work
     // relative to the canvas.
     RefPtr<RenderStyle> newStyle = RenderStyle::create();
+    canvas()->document().updateRenderTreeIfNeeded();
     if (RenderStyle* computedStyle = canvas()->computedStyle()) {
         FontDescription elementFontDescription(computedStyle->fontDescription());
         // Reset the computed size to avoid inheriting the zoom factor from the <canvas> element.
         elementFontDescription.setComputedSize(elementFontDescription.specifiedSize());
         newStyle->setFontDescription(elementFontDescription);
     } else {
         FontFamily fontFamily;
         fontFamily.setFamily(defaultFontFamily);
 
         FontDescription defaultFontDescription;
@@ skipping 539 matching lines @@
 
 unsigned CanvasRenderingContext2D::hitRegionsCount() const
 {
     if (m_hitRegionManager)
         return m_hitRegionManager->getHitRegionsCount();
 
     return 0;
 }
 
 } // namespace blink