Use Flow instead of PropTypes in Breakpoint and ColumnBreakpoint.

src/components/Editor/Breakpoint.js

@@ -1,5 +1,5 @@
 // @flow
-import { PropTypes, Component } from "react";
+import { Component } from "react";
 import { isEnabled } from "devtools-config";
 import ReactDOM from "../../../node_modules/react-dom/dist/react-dom";
 
@@ -20,6 +20,11 @@ function makeMarker(isDisabled: boolean) {
 }
 
 class Breakpoint extends Component {
+  props: {
+    breakpoint: Object,
+    editor: Object
+  };
+
   addBreakpoint: Function;
 
   constructor() {
@@ -77,11 +82,6 @@ class Breakpoint extends Component {
   }
 }
 
-Breakpoint.propTypes = {
-  breakpoint: PropTypes.object.isRequired,
-  editor: PropTypes.object.isRequired
-};
-
 Breakpoint.displayName = "Breakpoint";
 
 export default Breakpoint;

src/components/Editor/ColumnBreakpoint.js

@@ -1,5 +1,5 @@
 // @flow
-import { PropTypes, Component } from "react";
+import { Component } from "react";
 import { isEnabled } from "devtools-config";
 const ReactDOM = require("react-dom");
 import Svg from "../shared/Svg";
@@ -19,6 +19,11 @@ function makeBookmark() {
 }
 
 class ColumnBreakpoint extends Component {
+  props: {
+    breakpoint: Object,
+    editor: Object
+  };
+
   addBreakpoint: Function;
   bookmark: ?BookMarkType;
 
@@ -73,11 +78,6 @@ class ColumnBreakpoint extends Component {
   }
 }
 
-ColumnBreakpoint.propTypes = {
-  breakpoint: PropTypes.object.isRequired,
-  editor: PropTypes.object.isRequired
-};
-
 ColumnBreakpoint.displayName = "ColumnBreakpoint";
 
 export default ColumnBreakpoint;