From c0a73b2ed84ab0b542fd301274924ad782f09d47 Mon Sep 17 00:00:00 2001
From: Ron Buckton <rbuckton@microsoft.com>
Date: Thu, 8 Dec 2016 18:27:49 -0800
Subject: [PATCH] Revert changes to core.ts

---
 src/compiler/core.ts | 61 +++-----------------------------------------
 1 file changed, 4 insertions(+), 57 deletions(-)

diff --git a/src/compiler/core.ts b/src/compiler/core.ts
index 70674d400c3..72c09e490c3 100644
--- a/src/compiler/core.ts
+++ b/src/compiler/core.ts
@@ -571,32 +571,13 @@ namespace ts {
      * @param copyOnWrite Indicates whether to return a fresh array rather than modify the
      * existing array.
      */
-    export function append<T>(to: T[] | undefined, value: T | undefined, copyOnWrite?: boolean): T[] | undefined {
+    export function append<T>(to: T[] | undefined, value: T | undefined): T[] | undefined {
         if (value === undefined) return to;
         if (to === undefined) return [value];
-        if (copyOnWrite) return [...to, value];
         to.push(value);
         return to;
     }
 
-    /**
-     * Prepends a value to an array, returning the array.
-     *
-     * @param to The array to which `value` is to be prepended. If `to` is `undefined`, a new array
-     * is created if `value` was prepended.
-     * @param value The value to prepend to the array. If `value` is `undefined`, nothing is
-     * prepended.
-     * @param copyOnWrite Indicates whether to return a fresh array rather than modify the
-     * existing array.
-     */
-    export function prepend<T>(to: T[] | undefined, value: T | undefined, copyOnWrite?: boolean): T[] | undefined {
-        if (value === undefined) return to;
-        if (to === undefined) return [value];
-        if (copyOnWrite) return [value, ...to];
-        to.unshift(value);
-        return to;
-    }
-
     /**
      * Appends a range of value to an array, returning the array.
      *
@@ -604,45 +585,11 @@ namespace ts {
      * is created if `value` was appended.
      * @param from The values to append to the array. If `from` is `undefined`, nothing is
      * appended. If an element of `from` is `undefined`, that element is not appended.
-     * @param copyOnWrite Indicates whether to return a fresh array rather than modify the
-     * existing array.
      */
-    export function addRange<T>(to: T[] | undefined, from: T[] | undefined, copyOnWrite?: boolean): T[] | undefined {
+    export function addRange<T>(to: T[] | undefined, from: T[] | undefined): T[] | undefined {
         if (from === undefined) return to;
-        from = filter(from, isDefined);
-        if (to === undefined) return from;
-        if (from.length > 0) {
-            if (copyOnWrite) {
-                return [...to, ...from];
-            }
-            for (const v of from) {
-                to.push(v);
-            }
-        }
-        return to;
-    }
-
-    /**
-     * Appends a range of value to an array, returning the array.
-     *
-     * @param to The array to which `value` is to be appended. If `to` is `undefined`, a new array
-     * is created if `value` was appended.
-     * @param from The values to append to the array. If `from` is `undefined`, nothing is
-     * appended. If an element of `from` is `undefined`, that element is not appended.
-     * @param copyOnWrite Indicates whether to return a fresh array rather than modify the
-     * existing array.
-     */
-    export function prependRange<T>(to: T[] | undefined, from: T[] | undefined, copyOnWrite?: boolean): T[] | undefined {
-        if (from === undefined) return to;
-        from = filter(from, isDefined);
-        if (to === undefined) return from;
-        if (from.length > 0) {
-            if (copyOnWrite) {
-                return [...from, ...to];
-            }
-            for (let i = from.length - 1; i >= 0; i--) {
-                to.unshift(from[i]);
-            }
+        for (const v of from) {
+            to = append(to, v);
         }
         return to;
     }