fix(angular): module exports

angular/src/providers/nav-controller.ts

@@ -0,0 +1,34 @@
+import { Injectable } from '@angular/core';
+
+@Injectable()
+export class NavController {
+
+  private direction = 0;
+  private goBack = false;
+  private stack: string[] = [];
+
+  setGoback() {
+    this.goBack = true;
+  }
+
+  consumeDirection() {
+    if (this.direction === 0) {
+      const index = this.stack.indexOf(document.location.href);
+      if (index === -1) {
+        this.stack.push(document.location.href);
+        this.direction = 1;
+      } else if (index < this.stack.length - 1) {
+        this.stack = this.stack.slice(0, index + 1);
+        this.direction = -1;
+      }
+    }
+
+    const direction = this.goBack
+      ? -1
+      : this.direction;
+
+    this.goBack = false;
+    this.direction = 0;
+    return direction;
+  }
+}