FIR: Unmute passing blackbox tests

compiler/testData/codegen/box/bridges/covariantGenericDiamond.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 interface A {
     val result: Any
 }
@@ -9,4 +8,4 @@ interface B : A {
 abstract class AImpl<out Self : Any>(override val result: Self) : A
 class BImpl(result: String) : AImpl<String>(result), B
 
-fun box(): String = (BImpl("OK") as B).result
+fun box(): String = (BImpl("OK") as B).result