Fix build errors due to naive var->let replacement

src/compiler/commandLineParser.ts

@@ -320,8 +320,9 @@ namespace ts {
       * @param fileName The path to the config file
       */
     export function readConfigFile(fileName: string): { config?: any; error?: Diagnostic }  {
+        let text = '';
         try {
-            let text = sys.readFile(fileName);
+            text = sys.readFile(fileName);
         }
         catch (e) {
             return { error: createCompilerDiagnostic(Diagnostics.Cannot_read_file_0_Colon_1, fileName, e.message) };

src/compiler/emitter.ts

@@ -3783,7 +3783,7 @@ var __param = (this && this.__param) || function (paramIndex, decorator) {
                     emitDefaultValueAssignments(ctor);
                     emitRestParameter(ctor);
                     if (baseTypeElement) {
-                        let superCall = findInitialSuperCall(ctor);
+                        var superCall = findInitialSuperCall(ctor);
                         if (superCall) {
                             writeLine();
                             emit(superCall);

src/compiler/parser.ts

@@ -5647,8 +5647,9 @@ namespace ts {
             return;
 
             function visitNode(node: IncrementalNode) {
+                let text = '';
                 if (aggressiveChecks && shouldCheckNode(node)) {
-                    let text = oldText.substring(node.pos, node.end);
+                    text = oldText.substring(node.pos, node.end);
                 }
 
                 // Ditch any existing LS children we may have created.  This way we can avoid