Fixed Flow error

src/devtools/cache.js

@@ -13,7 +13,7 @@ import LRU from 'lru-cache';
 //    The size of this cache is bounded by how many renders were profiled,
 //    and it will be fully reset between profiling sessions.
 
-type Thenable<T> = {
+export type Thenable<T> = {
   then(resolve: (T) => mixed, reject: (mixed) => mixed): mixed,
 };
 

src/devtools/views/Components/InspectedElementContext.js

@@ -17,7 +17,7 @@ import type {
   InspectedElement,
   InspectedElementResponse,
 } from 'src/devtools/views/Components/types';
-import type { Resource } from '../../cache';
+import type { Resource, Thenable } from '../../cache';
 
 type Context = {|
   read(id: number): InspectedElement | null,
@@ -28,7 +28,7 @@ InspectedElementContext.displayName = 'InspectedElementContext';
 
 type ResolveFn = (inspectedElement: InspectedElement) => void;
 type InProgressRequest = {|
-  promise: Promise<InspectedElement>,
+  promise: Thenable<InspectedElement>,
   resolveFn: ResolveFn,
 |};