Prevent deopt when assigning double values to typed arrays

src/conversions.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 69 matching lines @@
 // Enumeration for allowing octals and ignoring junk when converting
 // strings to numbers.
 enum ConversionFlags {
   NO_FLAGS = 0,
   ALLOW_HEX = 1,
   ALLOW_OCTALS = 2,
   ALLOW_TRAILING_JUNK = 4
 };
 
 
+// Perform clamping values as defined by PixelArray semantics.
+static inline uint8_t ClampToUInt8(double number);
+
 // Convert from Number object to C integer.
 static inline int32_t NumberToInt32(Object* number);
 static inline uint32_t NumberToUint32(Object* number);
+static inline uint8_t NumberToClampedUInt8(Object* number);
 
 
 // Converts a string into a double value according to ECMA-262 9.3.1
 double StringToDouble(UnicodeCache* unicode_cache,
                       String* str,
                       int flags,
                       double empty_string_val = 0);
 double StringToDouble(UnicodeCache* unicode_cache,
                       Vector<const char> str,
                       int flags,
@@ skipping 19 matching lines @@
 // Additional number to string conversions for the number type.
 // The caller is responsible for calling free on the returned pointer.
 char* DoubleToFixedCString(double value, int f);
 char* DoubleToExponentialCString(double value, int f);
 char* DoubleToPrecisionCString(double value, int f);
 char* DoubleToRadixCString(double value, int radix);
 
 } }  // namespace v8::internal
 
 #endif  // V8_CONVERSIONS_H_