diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index f0c58c66bef..676a3afb561 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -2174,8 +2174,8 @@ namespace ts {
                 // A GetAccessor or SetAccessor is ES5 syntax.
                 excludeFlags = TransformFlags.MethodOrAccessorExcludes;
 
-                // A GetAccessor or SetAccessor is TypeScript syntax if it is either abstract,
-                // or has a decorator.
+                // A GetAccessor or SetAccessor is TypeScript syntax if it has async or abstract
+                // modifiers, or has a decorator.
                 if ((<AccessorDeclaration>node).body === undefined
                     || hasModifier(node, ModifierFlags.Async | ModifierFlags.Abstract)
                     || subtreeFlags & TransformFlags.ContainsDecorators) {
diff --git a/src/compiler/factory.ts b/src/compiler/factory.ts
index b21888514f1..5523baf54fd 100644
--- a/src/compiler/factory.ts
+++ b/src/compiler/factory.ts
@@ -1176,9 +1176,6 @@ namespace ts {
             const right = getMutableClone(node.right, emitOptions && clone(emitOptions));
             return createPropertyAccess(left, right, /*location*/ node, emitOptions && clone(emitOptions));
         }
-        else if (isIdentifier(node)) {
-            return getMutableClone(node, emitOptions && clone(emitOptions));
-        }
         else {
             return getMutableClone(node, emitOptions && clone(emitOptions));
         }
diff --git a/src/compiler/transformers/ts.ts b/src/compiler/transformers/ts.ts
index abc50d280a6..afc9e5b7570 100644
--- a/src/compiler/transformers/ts.ts
+++ b/src/compiler/transformers/ts.ts
@@ -228,9 +228,7 @@ namespace ts {
             if (hasModifier(node, ModifierFlags.Ambient) && isStatement(node)) {
                 // TypeScript ambient declarations are elided, but some comments may be preserved.
                 // See the implementation of `getLeadingComments` in comments.ts for more details.
-                return isStatement(node)
-                    ? createNotEmittedStatement(node)
-                    : undefined;
+                return createNotEmittedStatement(node);
             }
 
             switch (node.kind) {
@@ -430,16 +428,19 @@ namespace ts {
 
             const constructor = getFirstConstructorWithBody(node);
             if (constructor) {
-                for (const parameter of constructor.parameters) {
-                    if (parameter.decorators && parameter.decorators.length > 0) {
-                        return true;
-                    }
-                }
+                return forEach(constructor.parameters, shouldEmitDecorateCallForParameter);
             }
 
             return false;
         }
 
+        /**
+         * Tests whether we should emit a __decorate call for a parameter declaration.
+         */
+        function shouldEmitDecorateCallForParameter(parameter: ParameterDeclaration) {
+            return parameter.decorators !== undefined && parameter.decorators.length > 0;
+        }
+
         /**
          * Transforms a class declaration with TypeScript syntax into compatible ES6.
          *