[FIR] Fix various corner cases in DFA

compiler/testData/diagnostics/tests/smartCasts/safecalls/safeAccessReceiverNotNull.fir.kt

@@ -52,7 +52,7 @@ fun kt4565_1(a: SomeClass?) {
         a.data.hashCode()
     }
     if (a?.data is String) {
-        a.<!INAPPLICABLE_CANDIDATE!>data<!>.<!UNRESOLVED_REFERENCE!>length<!>
+        a.data.length
         data.length
     }
 }

compiler/testData/ir/irText/expressions/kt30020.fir.txt

@@ -58,7 +58,8 @@ FILE fqName:<root> fileName:/kt30020.kt
         $receiver: CALL 'public final fun CHECK_NOT_NULL <T0> (arg0: T0 of kotlin.internal.ir.CHECK_NOT_NULL?): T0 of kotlin.internal.ir.CHECK_NOT_NULL declared in kotlin.internal.ir' type=kotlin.collections.MutableList<kotlin.Any> origin=EXCLEXCL
           <T0>: kotlin.collections.MutableList<kotlin.Any>
           arg0: CALL 'public abstract fun f (): kotlin.collections.MutableList<kotlin.Any> declared in <root>.X' type=kotlin.collections.MutableList<kotlin.Any>? origin=null
-            $this: GET_VAR 'nx: <root>.X? declared in <root>.test' type=<root>.X? origin=null
+            $this: TYPE_OP type=<root>.X origin=IMPLICIT_CAST typeOperand=<root>.X
+              GET_VAR 'nx: <root>.X? declared in <root>.test' type=<root>.X? origin=null
         element: CONST Int type=kotlin.Int value=6
   FUN name:testExtensionReceiver visibility:public modality:FINAL <> ($receiver:kotlin.collections.MutableList<kotlin.Any>) returnType:kotlin.Unit
     $receiver: VALUE_PARAMETER name:<this> type:kotlin.collections.MutableList<kotlin.Any>