[test] Mute failing irText tests

compiler/testData/ir/irText/expressions/exhaustiveWhenElseBranch.kt

@@ -1,3 +1,6 @@
+// IGNORE_BACKEND_K2: JS_IR
+// IGNORE_BACKEND_K2: JS_IR_ES6
+
 enum class A { V1 }
 
 fun testVariableAssignment_throws(a: A) {
@@ -76,4 +79,4 @@ fun testLambdaResultExpression_throws(a: A) {
             // else -> throw
         }
     }()
-}
+}