[webdriver] Add Get All/Named Cookie Command {Simplify Test}

This was feedback on the PR.
#36171 (comment)

Bug: 1342633
Change-Id: Ia0a32f811d197e1e98b3952cdd192c7f7625f422
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3960128
Auto-Submit: Ari Chivukula <arichiv@chromium.org>
Commit-Queue: Mike Taylor <miketaylr@chromium.org>
Reviewed-by: Mike Taylor <miketaylr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1059912}

cookies/samesite/get_all_cookies-default-samesite.html

@@ -10,12 +10,9 @@
   document.cookie = "test0=0";
   const cookies = await test_driver.get_all_cookies();
   assert_equals(cookies.length, 1);
-  let cookieMap = new Map();
-  for (const cookie of cookies) {
-    cookieMap.set(cookie["name"], cookie);
-  }
-  assert_equals(cookieMap.get("test0")["name"], "test0");
-  assert_equals(cookieMap.get("test0")["value"], "0");
-  assert_equals(cookieMap.get("test0")["sameSite"], "Lax");
+  const cookie = cookies[0];
+  assert_equals(cookie["name"], "test0");
+  assert_equals(cookie["value"], "0");
+  assert_equals(cookie["sameSite"], "Lax");
 }, "Get all cookies w/ default SameSite");
 </script>