Expand C++ macros in tools/generate-runtime-tests.py to increase coverage

test/mjsunit/runtime-gen/dataviewgetfloat64.js

Index: test/mjsunit/runtime-gen/dataviewgetfloat64.js
diff --git a/test/mjsunit/runtime-gen/arraybufferisview.js b/test/mjsunit/runtime-gen/dataviewgetfloat64.js
similarity index 52%
copy from test/mjsunit/runtime-gen/arraybufferisview.js
copy to test/mjsunit/runtime-gen/dataviewgetfloat64.js
index def6b3be00071af822eb9ae4f220ee828d261183..82fc2205a65b9fab32530d52b4949d894149c597 100644
--- a/test/mjsunit/runtime-gen/arraybufferisview.js
+++ b/test/mjsunit/runtime-gen/dataviewgetfloat64.js
@@ -1,5 +1,7 @@
 // Copyright 2014 the V8 project authors. All rights reserved.
 // AUTO-GENERATED BY tools/generate-runtime-tests.py, DO NOT MODIFY
 // Flags: --allow-natives-syntax --harmony
-var _object = new Object();
-%ArrayBufferIsView(_object);
+var _holder = new DataView(new ArrayBuffer(24));
+var _offset = 1.5;
+var _is_little_endian = true;
+%DataViewGetFloat64(_holder, _offset, _is_little_endian);