Remove unnecessary variables for state and props (#8144)

The use of these variables confuses the ESLint plugin I use for VSCode.
It's also not useful.

ui/app/components/app/dropdowns/network-dropdown.js

@@ -126,7 +126,6 @@ class NetworkDropdown extends Component {
   }
 
   renderCommonRpc (rpcListDetail, provider) {
-    const props = this.props
     const reversedRpcListDetail = rpcListDetail.slice().reverse()
 
     return reversedRpcListDetail.map((entry) => {
@@ -143,7 +142,7 @@ class NetworkDropdown extends Component {
           <DropdownMenuItem
             key={`common${rpc}`}
             closeMenu={() => this.props.hideNetworkDropdown()}
-            onClick={() => props.setRpcTarget(rpc, chainId, ticker, nickname)}
+            onClick={() => this.props.setRpcTarget(rpc, chainId, ticker, nickname)}
             style={{
               fontSize: '16px',
               lineHeight: '20px',
@@ -170,7 +169,7 @@ class NetworkDropdown extends Component {
               className="fa fa-times delete"
               onClick={(e) => {
                 e.stopPropagation()
-                props.delRpcTarget(rpc)
+                this.props.delRpcTarget(rpc)
               }}
             />
           </DropdownMenuItem>

ui/app/components/app/token-cell/token-cell.component.js

@@ -48,7 +48,6 @@ export default class TokenCell extends Component {
 
   render () {
     const { tokenMenuOpen } = this.state
-    const props = this.props
     const {
       address,
       symbol,
@@ -62,7 +61,7 @@ export default class TokenCell extends Component {
       sidebarOpen,
       currentCurrency,
       image,
-    } = props
+    } = this.props
     let currentTokenToFiatRate
     let currentTokenInFiat
     let formattedFiat = ''

ui/app/components/app/token-list.js

@@ -132,8 +132,7 @@ class TokenList extends Component {
 
   render () {
     const { userAddress, assetImages } = this.props
-    const state = this.state
+    const { tokens, isLoading, error } = this.state
-    const { tokens, isLoading, error } = state
     if (isLoading) {
       return (
         <div