Add missing assert statements in equals.tentative.html.

The test cases for CSSMathClamp should have assert statements.

Bug: 1292345
Change-Id: I0bed4e8efe615f8e27d240c17ab71123c76aa62e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3439447
Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: 박중헌 <pjh0718@gmail.com>
Cr-Commit-Position: refs/heads/main@{#967546}

css/css-typed-om/stylevalue-subclasses/numeric-objects/equals.tentative.html

@@ -62,11 +62,13 @@
 test(() => {
   const a = new CSSMathClamp(1, 2, 3);
   const b = new CSSMathClamp(CSS.number(1), CSS.number(2), CSS.number(3));
+  assert_true(a.equals(b));
 }, 'Two CSSMathClamp with same value and unit are equal');
 
 test(() => {
   const a = new CSSMathClamp(1, 2, 3);
   const b = new CSSMathClamp(CSS.px(1), CSS.px(2), CSS.px(3));
+  assert_false(a.equals(b));
 }, 'Two CSSMathClamp with different units are not equal');
 
 </script>