Keep effectiveZoom finite

Source/core/css/CSSToLengthConversionData.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 74 matching lines @@
     float exFontSize() const { return m_fontSizes.ex(); }
     float chFontSize() const { return m_fontSizes.ch(); }
 
     // Accessing these marks the style as having viewport units
     double viewportWidthPercent() const;
     double viewportHeightPercent() const;
     double viewportMinPercent() const;
     double viewportMaxPercent() const;
 
     void setFontSizes(const FontSizes& fontSizes) { m_fontSizes = fontSizes; }
-    void setZoom(float zoom) { m_zoom = clampTo<float>(zoom, std::numeric_limits<float>::denorm_min()); }
+    void setZoom(float zoom)
+    {
+        ASSERT(std::isfinite(zoom) && zoom > 0);
+        m_zoom = zoom;
+    }
 
     CSSToLengthConversionData copyWithAdjustedZoom(float newZoom) const
     {
         return CSSToLengthConversionData(m_style, m_fontSizes, m_viewportSize, newZoom);
     }
 
 private:
     const ComputedStyle* m_style;
     FontSizes m_fontSizes;
     ViewportSize m_viewportSize;
     float m_zoom;
 };
 
 } // namespace blink
 
 #endif