Add Array.prototype.includes

Add Array.prototype.includes method. method of comments  I've quoted
from
[MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/includes).
And change Jakefiles.js to build lib.es7.d.ts.

src/lib/es7.d.ts

@@ -0,0 +1,89 @@
+interface Array<T> {
+    /**
+      * Determines whether an array includes a certain element, returning true or false as appropriate.
+      * @param searchElement The element to search for.
+      * @param fromIndex  The position in this array at which to begin searching for searchElement.
+      */
+    includes(searchElement: T, fromIndex?: number): boolean;
+}
+
+interface Int8Array {
+    /**
+      * Determines whether an array includes a certain element, returning true or false as appropriate.
+      * @param searchElement The element to search for.
+      * @param fromIndex  The position in this array at which to begin searching for searchElement.
+      */
+    includes(searchElement: Int8Array, fromIndex?: number): boolean;
+}
+
+interface Uint8Array {
+    /**
+      * Determines whether an array includes a certain element, returning true or false as appropriate.
+      * @param searchElement The element to search for.
+      * @param fromIndex  The position in this array at which to begin searching for searchElement.
+      */
+    includes(searchElement: number, fromIndex?: number): boolean;
+}
+
+interface Uint8ClampedArray {
+    /**
+      * Determines whether an array includes a certain element, returning true or false as appropriate.
+      * @param searchElement The element to search for.
+      * @param fromIndex  The position in this array at which to begin searching for searchElement.
+      */
+    includes(searchElement: number, fromIndex?: number): boolean;
+}
+
+interface Int16Array {
+    /**
+      * Determines whether an array includes a certain element, returning true or false as appropriate.
+      * @param searchElement The element to search for.
+      * @param fromIndex  The position in this array at which to begin searching for searchElement.
+      */
+    includes(searchElement: number, fromIndex?: number): boolean;
+}
+
+interface Uint16Array {
+    /**
+      * Determines whether an array includes a certain element, returning true or false as appropriate.
+      * @param searchElement The element to search for.
+      * @param fromIndex  The position in this array at which to begin searching for searchElement.
+      */
+    includes(searchElement: number, fromIndex?: number): boolean;
+}
+
+interface Int32Array {
+    /**
+      * Determines whether an array includes a certain element, returning true or false as appropriate.
+      * @param searchElement The element to search for.
+      * @param fromIndex  The position in this array at which to begin searching for searchElement.
+      */
+    includes(searchElement: number, fromIndex?: number): boolean;
+}
+
+interface Uint32Array {
+    /**
+      * Determines whether an array includes a certain element, returning true or false as appropriate.
+      * @param searchElement The element to search for.
+      * @param fromIndex  The position in this array at which to begin searching for searchElement.
+      */
+    includes(searchElement: number, fromIndex?: number): boolean;
+}
+
+interface Float32Array {
+    /**
+      * Determines whether an array includes a certain element, returning true or false as appropriate.
+      * @param searchElement The element to search for.
+      * @param fromIndex  The position in this array at which to begin searching for searchElement.
+      */
+    includes(searchElement: number, fromIndex?: number): boolean;
+}
+
+interface Float64Array {
+    /**
+      * Determines whether an array includes a certain element, returning true or false as appropriate.
+      * @param searchElement The element to search for.
+      * @param fromIndex  The position in this array at which to begin searching for searchElement.
+      */
+    includes(searchElement: number, fromIndex?: number): boolean;
+}