Use std:: on symbols declared in C++-style C headers.

src/bignum-dtoa.cc

 // Copyright 2011 the V8 project authors. 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 376 matching lines @@
   // floating-point imprecisions don't affect us.
   //
   // Explanation for v's boundary m+: the computation takes advantage of
   // the fact that 2^(p-1) <= f < 2^p. Boundaries still satisfy this requirement
   // (even for denormals where the delta can be much more important).
 
   const double k1Log10 = 0.30102999566398114;  // 1/lg(10)
 
   // For doubles len(f) == 53 (don't forget the hidden bit).
   const int kSignificandSize = 53;
-  double estimate = ceil((exponent + kSignificandSize - 1) * k1Log10 - 1e-10);
+  double estimate =
+      std::ceil((exponent + kSignificandSize - 1) * k1Log10 - 1e-10);
   return static_cast<int>(estimate);
 }
 
 
 // See comments for InitialScaledStartValues.
 static void InitialScaledStartValuesPositiveExponent(
     double v, int estimated_power, bool need_boundary_deltas,
     Bignum* numerator, Bignum* denominator,
     Bignum* delta_minus, Bignum* delta_plus) {
   // A positive exponent implies a positive power.
@@ skipping 241 matching lines @@
       delta_minus->Times10();
       delta_plus->AssignBignum(*delta_minus);
     } else {
       delta_minus->Times10();
       delta_plus->Times10();
     }
   }
 }
 
 } }  // namespace v8::internal