diff --git a/Libraries/CustomComponents/Navigator/Navigation/NavigationEvent.js b/Libraries/CustomComponents/Navigator/Navigation/NavigationEvent.js
index 5307e1f86..797097cac 100644
--- a/Libraries/CustomComponents/Navigator/Navigation/NavigationEvent.js
+++ b/Libraries/CustomComponents/Navigator/Navigation/NavigationEvent.js
@@ -27,7 +27,7 @@
  */
 'use strict';
 
-var invariant = require('fbjs/lib/invariant');
+const invariant = require('fbjs/lib/invariant');
 
 class NavigationEventPool {
   _list: Array<any>;
@@ -37,7 +37,7 @@ class NavigationEventPool {
   }
 
   get(type: string, currentTarget: Object, data: any): NavigationEvent {
-    var event;
+    let event;
     if (this._list.length > 0) {
       event = this._list.pop();
       event.constructor.call(event, type, currentTarget, data);
@@ -52,7 +52,7 @@ class NavigationEventPool {
   }
 }
 
-var _navigationEventPool = new NavigationEventPool();
+const _navigationEventPool = new NavigationEventPool();
 
 /**
  * The NavigationEvent interface represents any event of the navigation.
@@ -87,7 +87,7 @@ class NavigationEvent {
   _defaultPrevented: boolean;
   _disposed: boolean;
   _propagationStopped: boolean;
-  _type: ?string;
+  _type: string;
 
   target: ?Object;
 
@@ -111,22 +111,18 @@ class NavigationEvent {
     this._propagationStopped = false;
   }
 
-  /* $FlowFixMe - get/set properties not yet supported */
   get type(): string {
     return this._type;
   }
 
-  /* $FlowFixMe - get/set properties not yet supported */
-  get currentTarget(): Object {
+  get currentTarget(): ?Object {
     return this._currentTarget;
   }
 
-  /* $FlowFixMe - get/set properties not yet supported */
   get data(): any {
     return this._data;
   }
 
-  /* $FlowFixMe - get/set properties not yet supported */
   get defaultPrevented(): boolean {
     return this._defaultPrevented;
   }
@@ -160,7 +156,7 @@ class NavigationEvent {
     // Clean up.
     this.target = null;
     this.eventPhase = NavigationEvent.NONE;
-    this._type = null;
+    this._type = '';
     this._currentTarget = null;
     this._data = null;
     this._defaultPrevented = false;
diff --git a/Libraries/CustomComponents/Navigator/Navigation/NavigationRouteStack.js b/Libraries/CustomComponents/Navigator/Navigation/NavigationRouteStack.js
index f73ab10f0..3290ba462 100644
--- a/Libraries/CustomComponents/Navigator/Navigation/NavigationRouteStack.js
+++ b/Libraries/CustomComponents/Navigator/Navigation/NavigationRouteStack.js
@@ -61,12 +61,10 @@ class RouteStack {
     this._index = index;
   }
 
-  /* $FlowFixMe - get/set properties not yet supported */
   get size(): number {
     return this._routeNodes.size;
   }
 
-  /* $FlowFixMe - get/set properties not yet supported */
   get index(): number {
     return this._index;
   }
diff --git a/Libraries/Network/XMLHttpRequest.js b/Libraries/Network/XMLHttpRequest.js
index 529c2af64..793a9c13c 100644
--- a/Libraries/Network/XMLHttpRequest.js
+++ b/Libraries/Network/XMLHttpRequest.js
@@ -134,12 +134,10 @@ class XMLHttpRequest extends EventTarget(...XHR_EVENTS) {
     this._timedOut = false;
   }
 
-  // $FlowIssue #10784535
   get responseType(): ResponseType {
     return this._responseType;
   }
 
-  // $FlowIssue #10784535
   set responseType(responseType: ResponseType): void {
     if (this._sent) {
       throw new Error(
@@ -163,11 +161,10 @@ class XMLHttpRequest extends EventTarget(...XHR_EVENTS) {
     this._responseType = responseType;
   }
 
-  // $FlowIssue #10784535
   get responseText(): string {
     if (this._responseType !== '' && this._responseType !== 'text') {
       throw new Error(
-        `The 'responseText' property is only available if 'responseType' ` +
+        "The 'responseText' property is only available if 'responseType' " +
         `is set to '' or 'text', but it is '${this._responseType}'.`
       );
     }
@@ -177,7 +174,6 @@ class XMLHttpRequest extends EventTarget(...XHR_EVENTS) {
     return this._response;
   }
 
-  // $FlowIssue #10784535
   get response(): Response {
     const {responseType} = this;
     if (responseType === '' || responseType === 'text') {