Upgrade to compile with TS 3.3.3333

ts.compilerHost.getDirectories is now an optional field, so wrap access in a
nullablity check.

PiperOrigin-RevId: 237350326

internal/tsc_wrapped/compiler_host.ts

diff --git a/internal/tsc_wrapped/compiler_host.ts b/internal/tsc_wrapped/compiler_host.ts
index 04c35fd..911b82e 100644
--- a/internal/tsc_wrapped/compiler_host.ts
+++ b/internal/tsc_wrapped/compiler_host.ts
@@ -582,7 +582,8 @@
   }
 
   getDirectories(path: string) {
-    return this.delegate.getDirectories(path);
+    return this.delegate.getDirectories ? this.delegate.getDirectories(path) :
+                                          [];
   }
 
   readFile(fileName: string): string|undefined {