Revert "fix(compiler): Generates function expressions as returning any (#9980)"

This reverts commit eb5763c23f.

modules/@angular/compiler/src/output/ts_emitter.ts

@@ -170,7 +170,7 @@ class _TsEmitterVisitor extends AbstractEmitterVisitor implements o.TypeVisitor
     ctx.print(`(`);
     this._visitParams(ast.params, ctx);
     ctx.print(`):`);
-    this.visitType(ast.type, ctx);
+    this.visitType(ast.type, ctx, 'void');
     ctx.println(` => {`);
     ctx.incIndent();
     this.visitAllStatements(ast.statements, ctx);