test,benchmark: use deepStrictEqual()

In preparation for a lint rule that will enforce
assert.deepStrictEqual() over assert.deepEqual(), change tests and
benchmarks accordingly. For tests and benchmarks that are testing or
benchmarking assert.deepEqual() itself, apply a comment to ignore the
upcoming rule.

PR-URL: https://github.com/nodejs/node/pull/6213
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/parallel/test-fs-write-buffer.js

@@ -24,7 +24,7 @@ fs.open(filename, 'w', 0o644, function(err, fd) {
     fs.closeSync(fd);
 
     var found = fs.readFileSync(filename, 'utf8');
-    assert.deepEqual(expected.toString(), found);
+    assert.deepStrictEqual(expected.toString(), found);
     fs.unlinkSync(filename);
   });
 });