Fix FixedDoubleArray crashes in chromebot

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index e193dfc97710ba18b06d19282b011f9f6f87b372..df225b63f3fcc66734c27563908ee261584cd2ad 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -219,8 +219,20 @@ MUST_USE_RESULT static MaybeObject* DeepCopyBoilerplate(Isolate* isolate,
       }
       break;
     }
-    default:
-      UNREACHABLE();
+    case JSObject::NON_STRICT_ARGUMENTS_ELEMENTS:
+      UNIMPLEMENTED();
+      break;
+    case JSObject::EXTERNAL_PIXEL_ELEMENTS:
+    case JSObject::EXTERNAL_BYTE_ELEMENTS:
+    case JSObject::EXTERNAL_UNSIGNED_BYTE_ELEMENTS:
+    case JSObject::EXTERNAL_SHORT_ELEMENTS:
+    case JSObject::EXTERNAL_UNSIGNED_SHORT_ELEMENTS:
+    case JSObject::EXTERNAL_INT_ELEMENTS:
+    case JSObject::EXTERNAL_UNSIGNED_INT_ELEMENTS:
+    case JSObject::EXTERNAL_FLOAT_ELEMENTS:
+    case JSObject::EXTERNAL_DOUBLE_ELEMENTS:
+    case JSObject::FAST_DOUBLE_ELEMENTS:
+      // No contained objects, nothing to do.
       break;
   }
   return copy;