Treat <time> tag as a normal HTML tag. (#19951)

<time> tag has been supported by Chrome since Chrome 62.0.
Remove workarounds which were in place to avoid friction with
versions before Chrome 62.

Signed-off-by: Shivam Sandbhor <shivam.sandbhor@gmail.com>

packages/react-dom/src/__tests__/ReactDOMComponent-test.js

@@ -1273,10 +1273,6 @@ describe('ReactDOMComponent', () => {
           if (this instanceof window.HTMLUnknownElement) {
             return '[object HTMLUnknownElement]';
           }
-          // Special case! Read explanation below in the test.
-          if (this instanceof window.HTMLTimeElement) {
-            return '[object HTMLUnknownElement]';
-          }
           return realToString.apply(this, arguments);
         };
         Object.prototype.toString = wrappedToString; // eslint-disable-line no-extend-native
@@ -1289,11 +1285,6 @@ describe('ReactDOMComponent', () => {
           'The tag <foo> is unrecognized in this browser',
         );
         ReactTestUtils.renderIntoDocument(<foo />);
-        // This is a funny case.
-        // Chrome is the only major browser not shipping <time>. But as of July
-        // 2017 it intends to ship it due to widespread usage. We intentionally
-        // *don't* warn for <time> even if it's unrecognized by Chrome because
-        // it soon will be, and many apps have been using it anyway.
         ReactTestUtils.renderIntoDocument(<time />);
         // Corner case. Make sure out deduplication logic doesn't break with weird tag.
         expect(() =>

packages/react-dom/src/client/ReactDOMComponent.js

@@ -112,11 +112,6 @@ let normalizeHTML;
 
 if (__DEV__) {
   warnedUnknownTags = {
-    // Chrome is the only major browser not shipping <time>. But as of July
-    // 2017 it intends to ship it due to widespread usage. We intentionally
-    // *don't* warn for <time> even if it's unrecognized by Chrome because
-    // it soon will be, and many apps have been using it anyway.
-    time: true,
     // There are working polyfills for <dialog>. Let people use it.
     dialog: true,
     // Electron ships a custom <webview> tag to display external web content in