Chore: Upgrades typescript to version 3.5 (#18263)

* Chore: Upgrade typescript to version 3.5

public/app/core/components/Animations/SlideDown.tsx

@@ -41,7 +41,6 @@ export const SlideDown: FC<Props> = ({ children, in: inProp, maxHeight = default
           style={{
             ...style,
             ...transitionStyles[state],
-            inProp,
           }}
         >
           {children}

public/app/features/plugins/PluginPage.tsx

@@ -367,7 +367,7 @@ function getPluginTabsNav(
       }
 
       // Check for the dashboard pages
-      if (find(meta.includes, { type: 'dashboard' })) {
+      if (find(meta.includes, { type: PluginIncludeType.dashboard })) {
         pages.push({
           text: 'Dashboards',
           icon: 'gicon gicon-dashboard',