Don't calculate a top controls adjustment if pinch viewport size is uninitialized.

Source/wtf/MathExtras.h

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 335 matching lines @@
 
 template<typename T> inline T defaultMaximumForClamp() { return std::numeric_limits<T>::max(); }
 // This basically reimplements C++11's std::numeric_limits<T>::lowest().
 template<typename T> inline T defaultMinimumForClamp() { return std::numeric_limits<T>::min(); }
 template<> inline float defaultMinimumForClamp<float>() { return -std::numeric_limits<float>::max(); }
 template<> inline double defaultMinimumForClamp<double>() { return -std::numeric_limits<double>::max(); }
 
 // And, finally, the actual function for people to call.
 template<typename LimitType, typename ValueType> inline LimitType clampTo(ValueType value, LimitType min = defaultMinimumForClamp<LimitType>(), LimitType max = defaultMaximumForClamp<LimitType>())
 {
-    // FIXME: Uncomment this after fixing all callsites which violate it.
-    // ASSERT(!std::isnan(static_cast<double>(value)));
+    ASSERT(!std::isnan(static_cast<double>(value)));
     ASSERT(min <= max); // This also ensures |min| and |max| aren't NaN.
     return ClampToHelper<LimitType, ValueType>::clampTo(value, min, max);
 }
 
 inline bool isWithinIntRange(float x)
 {
     return x > static_cast<float>(std::numeric_limits<int>::min()) && x < static_cast<float>(std::numeric_limits<int>::max());
 }
 
 static size_t greatestCommonDivisor(size_t a, size_t b)
@@ skipping 53 matching lines @@
     if (i >> 2)
         log2 += 2, i >>= 2;
     if (i >> 1)
         log2 += 1;
     return log2;
 }
 
 } // namespace WTF
 
 #endif // #ifndef WTF_MathExtras_h