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

src/conversions-inl.h

 // 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 70 matching lines @@
     return negative ? ~result + 1 : result;
   }
   // Large number (outside uint32 range), Infinity or NaN.
   return 0x80000000u;  // Return integer indefinite.
 }
 
 
 inline double DoubleToInteger(double x) {
   if (std::isnan(x)) return 0;
   if (!std::isfinite(x) || x == 0) return x;
-  return (x >= 0) ? floor(x) : ceil(x);
+  return (x >= 0) ? std::floor(x) : std::ceil(x);
 }
 
 
 int32_t DoubleToInt32(double x) {
   int32_t i = FastD2I(x);
   if (FastI2D(i) == x) return i;
   Double d(x);
   int exponent = d.Exponent();
   if (exponent < 0) {
     if (exponent <= -Double::kSignificandSize) return 0;
@@ skipping 124 matching lines @@
 
   if (exponent == 0) {
     if (negative) {
       if (number == 0) return -0.0;
       number = -number;
     }
     return static_cast<double>(number);
   }
 
   ASSERT(number != 0);
-  return ldexp(static_cast<double>(negative ? -number : number), exponent);
+  return std::ldexp(static_cast<double>(negative ? -number : number), exponent);
 }
 
 
 template <class Iterator, class EndMark>
 double InternalStringToInt(UnicodeCache* unicode_cache,
                            Iterator current,
                            EndMark end,
                            int radix) {
   const bool allow_trailing_junk = true;
   const double empty_string_val = JunkStringValue();
@@ skipping 448 matching lines @@
   SLOW_ASSERT(buffer_pos < kBufferSize);
   buffer[buffer_pos] = '\0';
 
   double converted = Strtod(Vector<const char>(buffer, buffer_pos), exponent);
   return (sign == NEGATIVE) ? -converted : converted;
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_CONVERSIONS_INL_H_