Fix block param evaluation under older IE

lib/handlebars/compiler/compiler.js

@@ -1,5 +1,5 @@
 import Exception from "../exception";
-import {isArray} from "../utils";
+import {isArray, indexOf} from "../utils";
 import AST from "./ast";
 
 var slice = [].slice;
@@ -400,7 +400,7 @@ Compiler.prototype = {
   blockParamIndex: function(name) {
     for (var depth = 0, len = this.options.blockParams.length; depth < len; depth++) {
       var blockParams = this.options.blockParams[depth],
-          param = blockParams && blockParams.indexOf(name);
+          param = blockParams && indexOf(blockParams, name);
       if (blockParams && param >= 0) {
         return [depth, param];
       }

lib/handlebars/utils.js

@@ -48,6 +48,16 @@ export var isArray = Array.isArray || function(value) {
   return (value && typeof value === 'object') ? toString.call(value) === '[object Array]' : false;
 };
 
+// Older IE versions do not directly support indexOf so we must implement our own, sadly.
+export function indexOf(array, value) {
+  for (var i = 0, len = array.length; i < len; i++) {
+    if (array[i] === value) {
+      return i;
+    }
+  }
+  return -1;
+}
+
 
 export function escapeExpression(string) {
   // don't escape SafeStrings, since they're already safe