Add SIMD 128 alignment support to Heap.

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index ff9cc5b46b4cf1be4cb8eb636021ef1b00922d64..9e684927a86b862372c3d9a47b6c48bdfee11a02 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -1995,6 +1995,8 @@ int Heap::GetMaximumFillToAlign(AllocationAlignment alignment) {
     case kDoubleAligned:
     case kDoubleUnaligned:
       return kDoubleSize - kPointerSize;
+    case kSimd128Unaligned:
+      return kSimd128Size - kPointerSize;
     default:
       UNREACHABLE();
   }
@@ -2008,6 +2010,10 @@ int Heap::GetFillToAlign(Address address, AllocationAlignment alignment) {
     return kPointerSize;
   if (alignment == kDoubleUnaligned && (offset & kDoubleAlignmentMask) == 0)
     return kDoubleSize - kPointerSize;  // No fill if double is always aligned.
+  if (alignment == kSimd128Unaligned) {
+    return (kSimd128Size - (static_cast<int>(offset) + kPointerSize)) &
+           kSimd128AlignmentMask;
+  }
   return 0;
 }