[IconButton] Remove unused conditional

It appears that this conditional was added in 77a3d71, but even at that time,
there does not seem to be any calls to set the state of `hovered`, and so it it
always `undefined` which means we always are entering this `if` block.

src/IconButton/IconButton.js

@@ -171,11 +171,11 @@ class IconButton extends Component {
     if (keyboardFocused && !this.props.disabled) {
       this.showTooltip();
       if (this.props.onFocus) this.props.onFocus(event);
-    } else if (!this.state.hovered) {
-      this.hideTooltip();
-      if (this.props.onBlur) this.props.onBlur(event);
     }
 
+    this.hideTooltip();
+    if (this.props.onBlur) this.props.onBlur(event);
+
     if (this.props.onKeyboardFocus) {
       this.props.onKeyboardFocus(event, keyboardFocused);
     }