[[FIX]] Disallow dups in non-simple parameter list

Re-use the `(hasSimpleParams)` property of the `funct` object (recently
introduced to implement ES2016 restrictions on the "use strict"
directive) to honor the early error for duplicate parameters.

src/scope-manager.js

@@ -542,6 +542,15 @@ var scopeManager = function(state, predefined, exported, declared) {
     validateParams: function(isArrow) {
       var isStrict = state.isStrict();
       var currentFunctParamScope = _currentFunctBody["(parent)"];
+      // From ECMAScript 2017:
+      //
+      // > 14.1.2Static Semantics: Early Errors
+      // >
+      // > [...]
+      // > - It is a Syntax Error if IsSimpleParameterList of
+      // >   FormalParameterList is false and BoundNames of FormalParameterList
+      // >   contains any duplicate elements.
+      var isSimple = state.funct['(hasSimpleParams)'];
 
       if (!currentFunctParamScope["(params)"]) {
         return;
@@ -551,7 +560,7 @@ var scopeManager = function(state, predefined, exported, declared) {
         var label = currentFunctParamScope["(labels)"][labelName];
 
         if (label.duplicated) {
-          if (isStrict || isArrow) {
+          if (isStrict || isArrow || !isSimple) {
             warning("E011", label["(token)"], labelName);
           } else if (state.option.shadow !== true) {
             warning("W004", label["(token)"], labelName);

tests/test262/expectations.txt

@@ -618,8 +618,6 @@ test/language/expressions/object/method-definition/async-super-call-param.js(str
 test/language/expressions/object/method-definition/generator-param-init-yield.js(default)
 test/language/expressions/object/method-definition/generator-prop-name-yield-expr.js(default)
 test/language/expressions/object/method-definition/generator-prop-name-yield-id.js(default)
-test/language/expressions/object/method-definition/gen-meth-dflt-params-duplicates.js(default)
-test/language/expressions/object/method-definition/meth-dflt-params-duplicates.js(default)
 test/language/expressions/object/method-definition/name-param-id-yield.js(default)
 test/language/expressions/object/method-definition/name-param-init-yield.js(default)
 test/language/expressions/object/method-definition/name-prop-name-yield-expr.js(default)
@@ -2561,7 +2559,6 @@ test/built-ins/Function/prototype/toString/async-method-class-statement.js(stric
 test/built-ins/Function/prototype/toString/async-method-object.js(default)
 test/built-ins/Function/prototype/toString/async-method-object.js(strict mode)
 
-test/language/expressions/generators/dflt-params-duplicates.js(default)
 test/language/expressions/generators/dflt-params-ref-later.js(default)
 test/language/expressions/generators/dflt-params-ref-later.js(strict mode)
 test/language/expressions/generators/dflt-params-ref-self.js(default)
@@ -3608,7 +3605,6 @@ test/language/expressions/async-generator/yield-star-sync-return.js(default)
 test/language/expressions/async-generator/yield-star-sync-return.js(strict mode)
 test/language/expressions/async-generator/yield-star-sync-throw.js(default)
 test/language/expressions/async-generator/yield-star-sync-throw.js(strict mode)
-test/language/expressions/function/dflt-params-duplicates.js(default)
 test/language/expressions/function/dflt-params-ref-later.js(default)
 test/language/expressions/function/dflt-params-ref-later.js(strict mode)
 test/language/expressions/function/dflt-params-ref-self.js(default)
@@ -5989,7 +5985,6 @@ test/language/statements/for/dstr-const-obj-ptrn-rest-obj-nested-rest.js(default
 test/language/statements/for/dstr-const-obj-ptrn-rest-obj-nested-rest.js(strict mode)
 test/language/statements/for/dstr-const-obj-ptrn-rest-obj-own-property.js(default)
 test/language/statements/for/dstr-const-obj-ptrn-rest-obj-own-property.js(strict mode)
-test/language/statements/function/dflt-params-duplicates.js(default)
 test/language/statements/function/dflt-params-ref-later.js(default)
 test/language/statements/function/dflt-params-ref-later.js(strict mode)
 test/language/statements/function/dflt-params-ref-self.js(default)
@@ -6000,7 +5995,6 @@ test/language/statements/function/params-trailing-comma-multiple.js(default)
 test/language/statements/function/params-trailing-comma-multiple.js(strict mode)
 test/language/statements/function/params-trailing-comma-single.js(default)
 test/language/statements/function/params-trailing-comma-single.js(strict mode)
-test/language/statements/generators/dflt-params-duplicates.js(default)
 test/language/statements/generators/dflt-params-ref-later.js(default)
 test/language/statements/generators/dflt-params-ref-later.js(strict mode)
 test/language/statements/generators/dflt-params-ref-self.js(default)