Move collectGeneratorReturn into core

Author: weswigham

src/compiler/checker.ts

@@ -11791,14 +11791,6 @@ namespace ts {
             return result!.value as Type;
         }
 
-        function collectGeneratorReturn<TYield, TStep, TReturn>(gen: Generator<TYield, TReturn, TStep>, feedforward: (yielded: TYield) => TStep): TReturn {
-            let result;
-            for (result = gen.next(); !result.done;) {
-                result = gen.next(feedforward(result.value as TYield));
-            }
-            return (result as IteratorReturnResult<TReturn>).value;
-        }
-
         function getPermissiveInstantiation(type: Type) {
             return type.flags & (TypeFlags.Primitive | TypeFlags.AnyOrUnknown | TypeFlags.Never) ? type :
                 type.permissiveInstantiation || (type.permissiveInstantiation = instantiateType(type, permissiveMapper));

src/compiler/core.ts

@@ -582,6 +582,16 @@ namespace ts {
         return result;
     }
 
+
+    export function collectGeneratorReturn<TYield, TStep, TReturn>(gen: Generator<TYield, TReturn, TStep>, feedforward: (yielded: TYield) => TStep): TReturn {
+        let result;
+        for (result = gen.next(); !result.done;) {
+            result = gen.next(feedforward(result.value as TYield));
+        }
+        return (result as IteratorReturnResult<TReturn>).value;
+    }
+
+
     // Maps from T to T and avoids allocation if all elements map to themselves
     export function sameMap<T>(array: T[], f: (x: T, i: number) => T): T[];
     export function sameMap<T>(array: ReadonlyArray<T>, f: (x: T, i: number) => T): ReadonlyArray<T>;