Address PR comments and fix lint

Author: sandersn

src/compiler/checker.ts

@@ -3167,8 +3167,7 @@ namespace ts {
         /** Return the inferred type for a binding element */
         function getTypeForBindingElement(declaration: BindingElement): Type {
             const pattern = <BindingPattern>declaration.parent;
-            let parentType = getTypeForBindingElementParent(<VariableLikeDeclaration>pattern.parent);
-
+            const parentType = getTypeForBindingElementParent(<VariableLikeDeclaration>pattern.parent);
             // If parent has the unknown (error) type, then so does this binding element
             if (parentType === unknownType) {
                 return unknownType;

src/compiler/declarationEmitter.ts

@@ -333,10 +333,8 @@ namespace ts {
             }
             else {
                 errorNameNode = declaration.name;
-                let format = TypeFormatFlags.UseTypeOfFunction | TypeFormatFlags.UseTypeAliasValue;
-                if (shouldUseResolverType) {
-                    format |= TypeFormatFlags.AddUndefined;
-                }
+                const format = TypeFormatFlags.UseTypeOfFunction | TypeFormatFlags.UseTypeAliasValue |
+                    (shouldUseResolverType ? TypeFormatFlags.AddUndefined : 0);
                 resolver.writeTypeOfDeclaration(declaration, enclosingDeclaration, format, writer);
                 errorNameNode = undefined;
             }