Separate WeakMap to its own d.ts file.

Exclude in es6-shim compiles (Angular) to avoid name clashes.

declarations.d.ts

@@ -98,18 +98,6 @@ interface Console {
     dir(obj: any): void;
 }
 
-interface WeakMap<K, V> {
-    clear(): void;
-    delete(key: K): boolean;
-    get(key: K): V;
-    has(key: K): boolean;
-    set(key: K, value: V): WeakMap<K, V>;
-}
-
-declare var WeakMap: {
-    new <K, V>(): WeakMap<K, V>;
-}
-
 declare var console: Console;
 declare var global;
 declare var require;

weakmap.d.ts

@@ -0,0 +1,13 @@
+/* tslint:disable:no-unused-variable */
+
+interface WeakMap<K, V> {
+    clear(): void;
+    delete(key: K): boolean;
+    get(key: K): V;
+    has(key: K): boolean;
+    set(key: K, value: V): WeakMap<K, V>;
+}
+
+declare var WeakMap: {
+    new <K, V>(): WeakMap<K, V>;
+}