Eliminate unnecessary numeric equality checks

This commit changes the way numeric equality for number inputs works
such that it compares against `input.valueAsNumber`. This eliminates
quite a bit of branching around numeric equality.

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

@@ -16,7 +16,6 @@ import * as DOMPropertyOperations from './DOMPropertyOperations';
 import {getFiberCurrentPropsFromNode} from './ReactDOMComponentTree';
 import ReactControlledValuePropTypes from '../shared/ReactControlledValuePropTypes';
 import * as inputValueTracking from './inputValueTracking';
-import {shouldSetAttribute} from '../shared/DOMProperty.js';
 
 type InputWithWrapperState = HTMLInputElement & {
   _wrapperState: {
@@ -182,19 +181,9 @@ export function updateWrapper(element: Element, props: Object) {
   var value = getSafeValue(props.value);
 
   if (value != null) {
-    if (value === 0 && node.value === '') {
-      node.value = '0';
-      // Note: IE9 reports a number inputs as 'text', so check props instead.
-    } else if (props.type === 'number') {
-      // Simulate `input.valueAsNumber`. IE9 does not support it
-      var valueAsNumber = parseFloat(node.value) || 0;
-
-      if (
-        // eslint-disable-next-line
-        value != valueAsNumber ||
-        // eslint-disable-next-line
-        (value == valueAsNumber && node.value != value)
-      ) {
+    if (props.type === 'number') {
+      // eslint-disable-next-line
+      if (node.valueAsNumber !== value && node.value != value) {
         node.value = '' + value;
       }
     } else if (node.value !== '' + value) {
@@ -307,13 +296,9 @@ function updateNamedCousins(rootNode, props) {
 // when the user is inputting text
 //
 // https://github.com/facebook/react/issues/7253
-export function setDefaultValue(
-  node: InputWithWrapperState,
-  type: ?string,
-  value: *,
-) {
+export function setDefaultValue(node: InputWithWrapperState, type: ?string, value: *) {
   if (
-    // Focused number inputs synchronize on blur. See ChangeEventPlugin.js
+    // Focused number inputs set on blur. See ChangeEventPlugin.js
     type !== 'number' ||
     node.ownerDocument.activeElement !== node
   ) {