Components: Avoid body check on focus return unmount

Existed prior to refactoring to track events (#2321, #931).

Causes conflict where intentional tabs away from the mounted element would revert focus back to the element (twice tab to dismiss a tooltip'd element)

components/higher-order/with-focus-return/index.js

@@ -27,13 +27,20 @@ function withFocusReturn( WrappedComponent ) {
 		}
 
 		componentWillUnmount() {
+			this.returnFocus();
+		}
+
+		/**
+		 * Upon component unmount, verify whether focus is within the element
+		 * and, if it is, return focus to the element where focus had existed
+		 * at the point of component mount.
+		 */
+		returnFocus() {
 			const { activeElementOnMount, isFocused } = this;
-			if ( ! activeElementOnMount ) {
-				return;
-			}
 
-			const { body, activeElement } = document;
-			if ( isFocused || null === activeElement || body === activeElement ) {
+			// Verify there is an element to which focus should return, and
+			// that focus is within the wrapped element while unmount occurs.
+			if ( activeElementOnMount && isFocused ) {
 				activeElementOnMount.focus();
 			}
 		}

components/higher-order/with-focus-return/test/index.js

@@ -64,10 +64,6 @@ describe( 'withFocusReturn()', () => {
 			const mountedComposite = mount( <Composite /> );
 			expect( mountedComposite.instance().activeElementOnMount ).toBe( activeElement );
 
-			// Change activeElement.
-			document.activeElement.blur();
-			expect( document.activeElement ).toBe( document.body );
-
 			// Should return to the activeElement saved with this component.
 			mountedComposite.unmount();
 			expect( document.activeElement ).toBe( activeElement );