Allow references to ambient block scoped variables

Even when
1. --out or --outfile is specified
2. The block scoped variable's file is after the referrer's file.

src/compiler/checker.ts

@@ -737,7 +737,8 @@ namespace ts {
             const useFile = getSourceFileOfNode(usage);
             if (declarationFile !== useFile) {
                 if ((modulekind && (declarationFile.externalModuleIndicator || useFile.externalModuleIndicator)) ||
-                    (!compilerOptions.outFile && !compilerOptions.out)) {
+                    (!compilerOptions.outFile && !compilerOptions.out) ||
+                    isInAmbientContext(declaration)) {
                     // nodes are in different files and order cannot be determined
                     return true;
                 }