Make sure fixed typed array is always double aligned for doubles

src/globals.h

Index: src/globals.h
diff --git a/src/globals.h b/src/globals.h
index e71314f9c1af9558e6e249e16cdaab7dca870397..5b6aa26665b6744706d652061f9a2a546b9b76ec 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -640,6 +640,10 @@ struct AccessorDescriptor {
 #define CODE_POINTER_ALIGN(value)                               \
   (((value) + kCodeAlignmentMask) & ~kCodeAlignmentMask)
 
+// DOUBLE_POINTER_ALIGN returns the value algined for double pointers.
+#define DOUBLE_POINTER_ALIGN(value) \
+  (((value) + kDoubleAlignmentMask) & ~kDoubleAlignmentMask)
+
 // Support for tracking C++ memory allocation.  Insert TRACK_MEMORY("Fisk")
 // inside a C++ class and new and delete will be overloaded so logging is
 // performed.