Fix up linting errors

src/compiler/binder.ts

@@ -506,7 +506,7 @@ namespace ts {
             container = saveContainer;
             blockScopeContainer = savedBlockScopeContainer;
         }
-        
+
         function bindChildren(node: Node): void {
             if (skipTransformFlagAggregation) {
                 bindChildrenWorker(node);

src/compiler/transformers/ts.ts

@@ -627,7 +627,7 @@ namespace ts {
             //  ... = class ${name} ${heritageClauses} {
             //      ${members}
             //  }
-            let classExpression: Expression = setOriginalNode(
+            const classExpression: Expression = setOriginalNode(
                 createClassExpression(
                     name,
                     visitNodes(node.heritageClauses, visitor, isHeritageClause),

src/harness/harness.ts

@@ -769,7 +769,7 @@ namespace Harness {
                     return response.responseText;
                 }
                 else {
-                    return null;
+                    return undefined;
                 }
             }
 

src/harness/projectsRunner.ts

@@ -472,7 +472,7 @@ class ProjectRunner extends RunnerBase {
 
                     it("Baseline of emitted result (" + moduleNameToString(moduleKind) + "): " + testCaseFileName, () => {
                         if (testCase.baselineCheck) {
-                            var lastError: any = undefined;
+                            let lastError: any = undefined;
                             ts.forEach(compilerResult.outputFiles, outputFile => {
                                 try {
                                     Harness.Baseline.runBaseline("Baseline of emitted result (" + moduleNameToString(compilerResult.moduleKind) + "): " + testCaseFileName, getBaselineFolder(compilerResult.moduleKind) + outputFile.fileName, () => {