Replace the forbidReserved option with an allowReserved option

For consistency with similar options

README.md

@@ -63,8 +63,8 @@ object referring to that same position.
 - **onTrailingComma**: Like `onInsertedSemicolon`, but for trailing
   commas.
 
-- **forbidReserved**: If `true`, using a reserved word will generate
-  an error. Defaults to `false`. When given the value `"everywhere"`,
+- **allowReserved**: If `false`, using a reserved word will generate
+  an error. Defaults to `true`. When given the value `"never"`,
   reserved words and keywords can also not be used as property names
   (as in Internet Explorer's old parser).
   

acorn.js

@@ -60,11 +60,11 @@
     // `onTrailingComma` is similar to `onInsertedSemicolon`, but for
     // trailing commas.
     onTrailingComma: null,
-    // By default, reserved words are not enforced. Enable
-    // `forbidReserved` to enforce them. When this option has the
-    // value "everywhere", reserved words and keywords can also not be
+    // By default, reserved words are not enforced. Disable
+    // `allowReserved` to enforce them. When this option has the
+    // value "never", reserved words and keywords can also not be
     // used as property names.
-    forbidReserved: false,
+    allowReserved: true,
     // When enabled, a return at the top level is not considered an
     // error.
     allowReturnOutsideFunction: false,
@@ -2700,10 +2700,10 @@
 
   pp.parseIdent = function(liberal) {
     var node = this.startNode();
-    if (liberal && this.options.forbidReserved == "everywhere") liberal = false;
+    if (liberal && this.options.allowReserved == "never") liberal = false;
     if (this.type === tt.name) {
       if (!liberal &&
-          (this.options.forbidReserved &&
+          (!this.options.allowReserved &&
            (this.options.ecmaVersion === 3 ? isReservedWord3 : isReservedWord5)(this.value) ||
            this.strict && isStrictReservedWord(this.value)) &&
           this.input.slice(this.start, this.end).indexOf("\\") == -1)

test/tests-harmony.js

@@ -13871,7 +13871,7 @@ testFail("function hello() {'use strict'; ({ i: 10, s(eval) { } }); }", "Definin
 
 testFail("function a() { \"use strict\"; ({ b(t, t) { } }); }", "Argument name clash in strict mode (1:37)", {ecmaVersion: 6});
 
-testFail("var super", "The keyword 'super' is reserved (1:4)", {ecmaVersion: 6, forbidReserved: true});
+testFail("var super", "The keyword 'super' is reserved (1:4)", {ecmaVersion: 6, allowReserved: false});
 
 testFail("var default", "Unexpected token (1:4)", {ecmaVersion: 6});