Refactor and improve inlined double-aligned allocations

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index 1d56435487bd9e6bb05aae965bd225bc04c9881b..a3318dd451ee668291824e4e7f07fe5cea6bbe06 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -35,18 +35,6 @@
 namespace v8 {
 namespace internal {
 
-// Flags used for the AllocateInNewSpace functions.
-enum AllocationFlags {
-  // No special flags.
-  NO_ALLOCATION_FLAGS = 0,
-  // Return the pointer to the allocated already tagged as a heap object.
-  TAG_OBJECT = 1 << 0,
-  // The content of the result register already contains the allocation top in
-  // new space.
-  RESULT_CONTAINS_TOP = 1 << 1
-};
-
-
 // Default scratch register used by MacroAssembler (and other code that needs
 // a spare register). The register isn't callee save, and not used by the
 // function calling convention.