Add new Float32x4 type for SIMD.js.

src/heap-snapshot-generator.cc

Index: src/heap-snapshot-generator.cc
diff --git a/src/heap-snapshot-generator.cc b/src/heap-snapshot-generator.cc
index 9a78af6abe0cf2a2dc1d9c0b435db39d57109ce1..2cb8e3ff764e4d27fad79ef69f8e3bacb676a550 100644
--- a/src/heap-snapshot-generator.cc
+++ b/src/heap-snapshot-generator.cc
@@ -154,6 +154,7 @@ const char* HeapEntry::TypeAsString() {
     case kConsString: return "/concatenated string/";
     case kSlicedString: return "/sliced string/";
     case kSymbol: return "/symbol/";
+    case kSimdValue: return "/simd/";
     default: return "???";
   }
 }
@@ -861,6 +862,8 @@ HeapEntry* V8HeapExplorer::AddEntry(HeapObject* object) {
     return AddEntry(object, HeapEntry::kArray, "");
   } else if (object->IsHeapNumber()) {
     return AddEntry(object, HeapEntry::kHeapNumber, "number");
+  } else if (object->IsFloat32x4()) {
+    return AddEntry(object, HeapEntry::kSimdValue, "simd");
   }
   return AddEntry(object, HeapEntry::kHidden, GetSystemEntryName(object));
 }