Cache the result in DEV

In DEV it's somewhat likely that we'll see many logs that add component
stacks. This could be slow so we cache the results of previous components.

Author: sebmarkbage

packages/shared/ReactComponentStackFrame.js

@@ -53,6 +53,11 @@ export function describeBuiltInComponentFrame(
 }
 
 let reentry = false;
+let componentFrameCache;
+if (__DEV__) {
+  const PossiblyWeakMap = typeof WeakMap === 'function' ? WeakMap : Map;
+  componentFrameCache = new PossiblyWeakMap();
+}
 
 export function describeNativeComponentFrame(
   fn: Function,
@@ -63,6 +68,13 @@ export function describeNativeComponentFrame(
     return '';
   }
 
+  if (__DEV__) {
+    const frame = componentFrameCache.get(fn);
+    if (frame !== undefined) {
+      return frame;
+    }
+  }
+
   const control = Error();
 
   reentry = true;
@@ -119,7 +131,11 @@ export function describeNativeComponentFrame(
         if (sampleLines[s] !== controlLines[c]) {
           // Return the line we found.
           // V8 adds a "new" prefix for native classes. Let's remove it to make it prettier.
-          return '\n' + sampleLines[s - 1].replace(' at new ', ' at ');
+          const frame = '\n' + sampleLines[s - 1].replace(' at new ', ' at ');
+          if (__DEV__) {
+            componentFrameCache.set(fn, frame);
+          }
+          return frame;
         }
       }
     }
@@ -132,7 +148,11 @@ export function describeNativeComponentFrame(
   }
   // Fallback to just using the name if we couldn't make it throw.
   const name = fn ? fn.displayName || fn.name : '';
-  return name ? describeBuiltInComponentFrame(name) : '';
+  const syntheticFrame = name ? describeBuiltInComponentFrame(name) : '';
+  if (__DEV__) {
+    componentFrameCache.set(fn, syntheticFrame);
+  }
+  return syntheticFrame;
 }
 
 const BEFORE_SLASH_RE = /^(.*)[\\\/]/;