Move GridCache to browser

src/browser/renderer/GridCache.ts

@@ -0,0 +1,33 @@
+/**
+ * Copyright (c) 2017 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+export class GridCache<T> {
+  public cache: (T | undefined)[][];
+
+  public constructor() {
+    this.cache = [];
+  }
+
+  public resize(width: number, height: number): void {
+    for (let x = 0; x < width; x++) {
+      if (this.cache.length <= x) {
+        this.cache.push([]);
+      }
+      for (let y = this.cache[x].length; y < height; y++) {
+        this.cache[x].push(undefined);
+      }
+      this.cache[x].length = height;
+    }
+    this.cache.length = width;
+  }
+
+  public clear(): void {
+    for (let x = 0; x < this.cache.length; x++) {
+      for (let y = 0; y < this.cache[x].length; y++) {
+        this.cache[x][y] = undefined;
+      }
+    }
+  }
+}