Fix lint warnings

Author: rbuckton

src/compiler/transformers/es2015.ts

@@ -862,7 +862,7 @@ namespace ts {
          *                            synthesized `super` call.
          */
         function transformConstructorBody(constructor: ConstructorDeclaration | undefined, node: ClassDeclaration | ClassExpression, extendsClauseElement: ExpressionWithTypeArguments, hasSynthesizedSuper: boolean) {
-            let statements: Statement[] = [];
+            const statements: Statement[] = [];
             resumeLexicalEnvironment();
 
             let statementOffset = -1;

src/compiler/transformers/module/module.ts

@@ -80,7 +80,7 @@ namespace ts {
         function transformCommonJSModule(node: SourceFile) {
             startLexicalEnvironment();
 
-            let statements: Statement[] = [];
+            const statements: Statement[] = [];
             const statementOffset = addPrologueDirectives(statements, node.statements, /*ensureUseStrict*/ !compilerOptions.noImplicitUseStrict, sourceElementVisitor);
             append(statements, visitNode(currentModuleInfo.externalHelpersImportDeclaration, sourceElementVisitor, isStatement, /*optional*/ true));
             addRange(statements, visitNodes(node.statements, sourceElementVisitor, isStatement, statementOffset));
@@ -255,7 +255,7 @@ namespace ts {
         function transformAsynchronousModuleBody(node: SourceFile) {
             startLexicalEnvironment();
 
-            let statements: Statement[] = [];
+            const statements: Statement[] = [];
             const statementOffset = addPrologueDirectives(statements, node.statements, /*ensureUseStrict*/ !compilerOptions.noImplicitUseStrict, sourceElementVisitor);
 
             // Visit each statement of the module body.

src/compiler/transformers/ts.ts

@@ -2470,7 +2470,7 @@ namespace ts {
             const savedCurrentNamespaceLocalName = currentNamespaceContainerName;
             currentNamespaceContainerName = localName;
 
-            let statements: Statement[] = [];
+            const statements: Statement[] = [];
             startLexicalEnvironment();
             addRange(statements, map(node.members, transformEnumMember));
             addRange(statements, endLexicalEnvironment());
@@ -2753,7 +2753,7 @@ namespace ts {
             currentNamespace = node;
             currentScopeFirstDeclarationsOfName = undefined;
 
-            let statements: Statement[] = [];
+            const statements: Statement[] = [];
             startLexicalEnvironment();
 
             let statementsLocation: TextRange;