[FIR] Fix wrong ConstantReference for returnsNotNull in EffectExtractor

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/deeplyNested.fir.kt

@@ -68,12 +68,12 @@ fun nested2(x: Any?) {
 
 fun nested3(x: Any?) {
     myAssert(equalsTrue(notEqualsNull(nullWhenNotString(x))))
-    x.<!UNRESOLVED_REFERENCE!>length<!>
+    x.length
 }
 
 fun branchedAndNested(x: Any?, y: Any?) {
     myAssert(equalsTrue(notEqualsNull(nullWhenNotString(x))) && equalsTrue(isString(y)))
-    x.<!UNRESOLVED_REFERENCE!>length<!>
+    x.length
     y.length
 }
 
@@ -97,7 +97,7 @@ fun branchedAndNestedWithNativeOperators(x: Any?, y: Any?) {
             &&
             (1 == 2 || y is Int || isString(y))
     )
-    x.<!UNRESOLVED_REFERENCE!>length<!>
+    x.length
     y.length
     y.inc()
 }

compiler/testData/diagnostics/testsWithStdLib/contracts/smartcasts/nullabilitySmartcastWhenNullability.fir.kt

@@ -14,17 +14,17 @@ fun nullWhenNull(x: Int?): Int? {
 
 fun testNullWhenNull(x: Int?) {
     if (nullWhenNull(x) == null) {
-        x.dec()
+        x.<!AMBIGUITY!>dec<!>()
     }
     else {
-        x.<!AMBIGUITY!>dec<!>()
+        x.dec()
     }
 
     if (nullWhenNull(x) != null) {
-        x.<!AMBIGUITY!>dec<!>()
+        x.dec()
     }
     else {
-        x.dec()
+        x.<!AMBIGUITY!>dec<!>()
     }
 
     x.<!AMBIGUITY!>dec<!>()