Fix crash when checking module exports for export=

Also make maxNodeModuleJsDepth default to 0 so that incorrect tsconfigs
now let the compiler spend less time compiling JS that is found in
node_modules (especially since most people will already have the d.ts
and want ignore the JS anyway). jsconfig still defaults to 2.

src/compiler/commandLineParser.ts

@@ -885,7 +885,7 @@ namespace ts {
     function convertCompilerOptionsFromJsonWorker(jsonOptions: any,
         basePath: string, errors: Diagnostic[], configFileName?: string): CompilerOptions {
 
-        const options: CompilerOptions = getBaseFileName(configFileName) === "jsconfig.json" ? { allowJs: true } : {};
+        const options: CompilerOptions = getBaseFileName(configFileName) === "jsconfig.json" ? { allowJs: true, maxNodeModuleJsDepth: 2 } : {};
         convertOptionsFromJson(optionDeclarations, jsonOptions, basePath, options, Diagnostics.Unknown_compiler_option_0, errors);
         return options;
     }