Fix sky include guards to match Chromium style

sky/engine/wtf/dtoa/fixed-dtoa.h

 // Copyright 2010 the V8 project authors. All rights reserved.
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-#ifndef DOUBLE_CONVERSION_FIXED_DTOA_H_
-#define DOUBLE_CONVERSION_FIXED_DTOA_H_
+#ifndef SKY_ENGINE_WTF_DTOA_FIXED-DTOA_H_
+#define SKY_ENGINE_WTF_DTOA_FIXED-DTOA_H_
 
 #include "sky/engine/wtf/dtoa/utils.h"
 
 namespace WTF {
 
 namespace double_conversion {
 
     // Produces digits necessary to print a given number with
     // 'fractional_count' digits after the decimal point.
     // The buffer must be big enough to hold the result plus one terminating null
@@ skipping 10 matching lines @@
     //
     // This method only works for some parameters. If it can't handle the input it
     // returns false. The output is null-terminated when the function succeeds.
     bool FastFixedDtoa(double v, int fractional_count,
                        Vector<char> buffer, int* length, int* decimal_point);
 
 }  // namespace double_conversion
 
 } // namespace WTF
 
-#endif  // DOUBLE_CONVERSION_FIXED_DTOA_H_
+#endif  // SKY_ENGINE_WTF_DTOA_FIXED-DTOA_H_