Data flow values: STABLE_COMPLEX_EXPRESSION kind is removed, no use cases exist for them

compiler/resolution/src/org/jetbrains/kotlin/resolve/calls/smartcasts/DataFlowValue.kt

@@ -39,8 +39,6 @@ class DataFlowValue(val identifierInfo: IdentifierInfo,
         // or protected / public member value from the same module without open / custom getter
         // Smart casts are completely safe
         STABLE_VALUE("stable"),
-        // Block, or if / else, or when, or (in future) some other complex expression
-        STABLE_COMPLEX_EXPRESSION("complex expression", ""),
         // Member value with open / custom getter
         // Smart casts are not safe
         PROPERTY_WITH_GETTER("custom getter", "property that has open or custom getter"),
@@ -70,7 +68,7 @@ class DataFlowValue(val identifierInfo: IdentifierInfo,
      * Predictable means here we do not expect some sudden change of their values,
      * like accessing mutable properties in another thread, so smart casts can be used safely.
      */
-    val isPredictable = (kind == Kind.STABLE_VALUE || kind == Kind.STABLE_COMPLEX_EXPRESSION || kind == Kind.PREDICTABLE_VARIABLE)
+    val isPredictable = (kind == Kind.STABLE_VALUE || kind == Kind.PREDICTABLE_VARIABLE)
         @JvmName("isPredictable") get
 
     override fun equals(other: Any?): Boolean {