Fix propTypes and test props for SignatureRequest component (#7849)

ui/app/components/app/signature-request/signature-request-header/signature-request-header.component.js

@@ -5,7 +5,7 @@ import NetworkDisplay from '../../network-display'
 
 export default class SignatureRequestHeader extends PureComponent {
   static propTypes = {
-    selectedAccount: PropTypes.object.isRequired,
+    selectedAccount: PropTypes.object,
   }
 
   render () {

ui/app/components/app/signature-request/signature-request.component.js

@@ -14,7 +14,7 @@ export default class SignatureRequest extends PureComponent {
       address: PropTypes.string,
       balance: PropTypes.string,
       name: PropTypes.string,
-    }).isRequired,
+    }),
 
     clearConfirmTransaction: PropTypes.func.isRequired,
     cancel: PropTypes.func.isRequired,

ui/app/components/app/signature-request/tests/signature-request.test.js

@@ -10,6 +10,9 @@ describe('Signature Request Component', function () {
   beforeEach(() => {
     wrapper = shallow((
       <SignatureRequest
+        clearConfirmTransaction={() => {}}
+        cancel={() => {}}
+        sign={() => {}}
         txData={{
           msgParams: {
             data: '{"message": {"from": {"name": "hello"}}}',