Fix back-forward highlight state

By updating the state on loadEnd and not loadStart

Auditors: @bsclifton

Fix #5735

js/components/frame.js

@@ -924,10 +924,6 @@ class Frame extends ImmutableComponent {
           runInsecureContent: false
         })
       }
-      windowActions.updateBackForwardState(
-        this.frame,
-        this.webview.canGoBack(),
-        this.webview.canGoForward())
       const hack = siteHacks[parsedUrl.hostname]
       if (hack && hack.pageLoadStartScript) {
         this.webview.executeJavaScript(hack.pageLoadStartScript)
@@ -940,6 +936,10 @@ class Frame extends ImmutableComponent {
       windowActions.onWebviewLoadEnd(
         this.frame,
         this.webview.getURL())
+      windowActions.updateBackForwardState(
+        this.frame,
+        this.webview.canGoBack(),
+        this.webview.canGoForward())
 
       const parsedUrl = urlParse(this.props.location)
       if (!this.allowRunningWidevinePlugin()) {

test/components/frameTest.js

@@ -118,6 +118,31 @@ describe('frame tests', function () {
       })
     })
 
+    describe('back-forward state', function () {
+      Brave.beforeAll(this)
+      before(function * () {
+        this.url1 = Brave.server.url('page1.html')
+        yield setup(this.app.client)
+        yield this.app.client
+          .waitForExist('.navigationButtonContainer.disabled .backButton')
+          .tabByIndex(0)
+          // add some history
+          .loadUrl(this.url1)
+          .windowByUrl(Brave.browserWindowUrl)
+      })
+
+      it('enables back button on first nav', function * () {
+        yield this.app.client
+          .waitForExist('.navigationButtonContainer:not(.disabled) .backButton')
+      })
+
+      it('enables forward button after pressing back', function * () {
+        yield this.app.client
+          .click(backButton)
+          .waitForExist('.navigationButtonContainer:not(.disabled) .forwardButton')
+      })
+    })
+
     describe('back clone', function () {
       Brave.beforeAll(this)