remove warn throwing since console.warn includes callsites now

src/utils/warn.js

@@ -16,15 +16,6 @@ function warn(message, ...args) {
   if (typeof console !== 'undefined') {
     console.warn(`Warning: ${message}`, ...args) // eslint-disable-line no-console
   }
-
-  try {
-    // --- Welcome to debugging Slate! ---
-    // This error was thrown as a convenience so that you can use this stack
-    // to find the callsite that caused this warning to fire.
-    throw new Error(message)
-  } catch (x) {
-    // This error is only for debugging.
-  }
 }
 
 /**