Restore knownHelpersOnly throw

Fixes #302

lib/handlebars/compiler/compiler.js

@@ -272,7 +272,7 @@ Compiler.prototype = {
 
     if (this.options.knownHelpers[name]) {
       this.opcode('invokeKnownHelper', params.length, name);
-    } else if (this.knownHelpersOnly) {
+    } else if (this.options.knownHelpersOnly) {
       throw new Error("You specified knownHelpersOnly, but used the unknown helper " + name);
     } else {
       this.opcode('invokeHelper', params.length, name);

spec/qunit_spec.js

@@ -709,6 +709,11 @@ test("Functions are bound to the context in knownHelpers only mode", function()
   var result = template({foo: function() { return this.bar; }, bar: 'bar'});
   equal(result, "bar", "'bar' should === '" + result);
 });
+test("Unknown helper call in knownHelpers only mode should throw", function() {
+  shouldThrow(function() {
+    CompilerContext.compile("{{typeof hello}}", {knownHelpersOnly: true});
+  }, Error, 'specified knownHelpersOnly');
+});
 
 suite("blockHelperMissing");