fix(color-contrast): do not run on elements with font-size: 0 (#4822)

Closes #4820

Author: straker

lib/rules/color-contrast-matches.js

@@ -137,6 +137,10 @@ function colorContrastMatches(node, virtualNode) {
     return false;
   }
 
+  if (!parseFloat(virtualNode.getComputedStylePropertyValue('font-size'))) {
+    return false;
+  }
+
   const range = document.createRange();
   const childNodes = virtualNode.children;
   for (let index = 0; index < childNodes.length; index++) {

test/integration/rules/color-contrast/color-contrast.html

@@ -465,3 +465,10 @@
     <div id="ignore13" style="padding-left: 65px">Hello World</div>
   </div>
 </div>
+
+<div
+  id="ignore13"
+  style="background-color: gray; color: white; font-size: 0; font-weight: bold"
+>
+  Ignore.
+</div>

test/rule-matches/color-contrast-matches.js

@@ -431,6 +431,13 @@ describe('color-contrast-matches', function () {
     assert.isFalse(rule.matches(target, axe.utils.getNodeFromTree(target)));
   });
 
+  it('should not match text with font-size: 0', () => {
+    fixture.innerHTML = '<div style="font-size: 0">hi</div>';
+    const target = fixture.querySelector('div');
+    axe.testUtils.flatTreeSetup(fixture);
+    assert.isFalse(rule.matches(target, axe.utils.getNodeFromTree(target)));
+  });
+
   if (shadowSupport) {
     it('should match a descendant of an element across a shadow boundary', function () {
       fixture.innerHTML =