diff --git a/packages/polyfill/index.ts b/packages/polyfill/index.ts
index 21b16b16ee6..f3714ae33fa 100644
--- a/packages/polyfill/index.ts
+++ b/packages/polyfill/index.ts
@@ -15,5 +15,5 @@
  */
 
 import './src/polyfills/promise';
-import './src/shims/find';
-import './src/shims/findIndex';
+import './src/shims/Array';
+import './src/shims/String';
diff --git a/packages/polyfill/src/shims/findIndex.ts b/packages/polyfill/src/shims/Array.ts
similarity index 58%
rename from packages/polyfill/src/shims/findIndex.ts
rename to packages/polyfill/src/shims/Array.ts
index 325c7f0d59d..798a4f3a343 100644
--- a/packages/polyfill/src/shims/findIndex.ts
+++ b/packages/polyfill/src/shims/Array.ts
@@ -14,6 +14,55 @@
  * limitations under the License.
  */
 
+/**
+ * This is the Array.prototype.find polyfill from MDN
+ * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find
+ * https://tc39.github.io/ecma262/#sec-array.prototype.find
+ */
+if (!Array.prototype.find) {
+  Object.defineProperty(Array.prototype, 'find', {
+    value: function(predicate) {
+      // 1. Let O be ? ToObject(this value).
+      if (this == null) {
+        throw new TypeError('"this" is null or not defined');
+      }
+
+      var o = Object(this);
+
+      // 2. Let len be ? ToLength(? Get(O, "length")).
+      var len = o.length >>> 0;
+
+      // 3. If IsCallable(predicate) is false, throw a TypeError exception.
+      if (typeof predicate !== 'function') {
+        throw new TypeError('predicate must be a function');
+      }
+
+      // 4. If thisArg was supplied, let T be thisArg; else let T be undefined.
+      var thisArg = arguments[1];
+
+      // 5. Let k be 0.
+      var k = 0;
+
+      // 6. Repeat, while k < len
+      while (k < len) {
+        // a. Let Pk be ! ToString(k).
+        // b. Let kValue be ? Get(O, Pk).
+        // c. Let testResult be ToBoolean(? Call(predicate, T, « kValue, k, O »)).
+        // d. If testResult is true, return kValue.
+        var kValue = o[k];
+        if (predicate.call(thisArg, kValue, k, o)) {
+          return kValue;
+        }
+        // e. Increase k by 1.
+        k++;
+      }
+
+      // 7. Return undefined.
+      return undefined;
+    }
+  });
+}
+
 /**
  * This is the Array.prototype.findIndex polyfill from MDN
  * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findIndex
diff --git a/packages/polyfill/src/shims/String.ts b/packages/polyfill/src/shims/String.ts
new file mode 100644
index 00000000000..c8c006f7c15
--- /dev/null
+++ b/packages/polyfill/src/shims/String.ts
@@ -0,0 +1,25 @@
+/**
+ * Copyright 2018 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * This is the String.prototype.startsWith polyfill from MDN
+ * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/startsWith
+ */
+if (!String.prototype.startsWith) {
+  String.prototype.startsWith = function(search, pos) {
+    return this.substr(!pos || pos < 0 ? 0 : +pos, search.length) === search;
+  };
+}
diff --git a/packages/polyfill/src/shims/find.ts b/packages/polyfill/src/shims/find.ts
deleted file mode 100644
index 587e23ddb67..00000000000
--- a/packages/polyfill/src/shims/find.ts
+++ /dev/null
@@ -1,64 +0,0 @@
-/**
- * Copyright 2017 Google Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-/**
- * This is the Array.prototype.find polyfill from MDN
- * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/find
- * https://tc39.github.io/ecma262/#sec-array.prototype.find
- */
-if (!Array.prototype.find) {
-  Object.defineProperty(Array.prototype, 'find', {
-    value: function(predicate) {
-      // 1. Let O be ? ToObject(this value).
-      if (this == null) {
-        throw new TypeError('"this" is null or not defined');
-      }
-
-      var o = Object(this);
-
-      // 2. Let len be ? ToLength(? Get(O, "length")).
-      var len = o.length >>> 0;
-
-      // 3. If IsCallable(predicate) is false, throw a TypeError exception.
-      if (typeof predicate !== 'function') {
-        throw new TypeError('predicate must be a function');
-      }
-
-      // 4. If thisArg was supplied, let T be thisArg; else let T be undefined.
-      var thisArg = arguments[1];
-
-      // 5. Let k be 0.
-      var k = 0;
-
-      // 6. Repeat, while k < len
-      while (k < len) {
-        // a. Let Pk be ! ToString(k).
-        // b. Let kValue be ? Get(O, Pk).
-        // c. Let testResult be ToBoolean(? Call(predicate, T, « kValue, k, O »)).
-        // d. If testResult is true, return kValue.
-        var kValue = o[k];
-        if (predicate.call(thisArg, kValue, k, o)) {
-          return kValue;
-        }
-        // e. Increase k by 1.
-        k++;
-      }
-
-      // 7. Return undefined.
-      return undefined;
-    }
-  });
-}