Avoid "Member not found" error in IE (#7411)

Greg Palmer · zpao · commit 08dbefedc7dc · 2016-09-15T16:32:45.000-07:00
Explanation, discussion, and similar change as #7343 Addresses #7320 (cherry picked from commit a874196)
diff --git a/src/renderers/dom/client/syntheticEvents/SyntheticEvent.js b/src/renderers/dom/client/syntheticEvents/SyntheticEvent.js
@@ -121,7 +121,7 @@ Object.assign(SyntheticEvent.prototype, {
 
     if (event.preventDefault) {
       event.preventDefault();
-    } else {
+    } else if (typeof event.returnValue !== 'unknown') { // eslint-disable-line valid-typeof
       event.returnValue = false;
     }
     this.isDefaultPrevented = emptyFunction.thatReturnsTrue;

Original file line number	Diff line number	Diff line change
`@@ -121,7 +121,7 @@ Object.assign(SyntheticEvent.prototype, {`
`121`	`121`
`122`	`122`	`if (event.preventDefault) {`
`123`	`123`	`event.preventDefault();`
`124`		`- } else {`
	`124`	`+ } else if (typeof event.returnValue !== 'unknown') { // eslint-disable-line valid-typeof`
`125`	`125`	`event.returnValue = false;`
`126`	`126`	`}`
`127`	`127`	`this.isDefaultPrevented = emptyFunction.thatReturnsTrue;`