[v34] Add arm64 architecture in double-conversion

Author: pandamicro

mfbt/double-conversion/utils.h

@@ -60,7 +60,8 @@
     defined(__sparc__) || defined(__sparc) || defined(__s390__) || \
     defined(__SH4__) || defined(__alpha__) || \
     defined(_MIPS_ARCH_MIPS32R2) || \
-    defined(__AARCH64EL__)
+    defined(_AARCH64EL_) || \
+    defined(__arm64__)
 #define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
 #elif defined(_M_IX86) || defined(__i386__) || defined(__i386)
 #if defined(_WIN32)