Remove unnecessary I2 from test case

Author: DanCorder

tests/cases/fourslash/completionListImplementingInterfaceFunctions.ts

@@ -10,12 +10,7 @@
 ////    /*0*/
 ////}
 ////
-////interface I2 {
-////    a(): void;
-////    b(): void;
-////}
-////
-////var imp2: I2 {
+////var imp2: I1 {
 ////    a: () => {},
 ////    /*1*/
 ////}