[NI] Avoid computing few things for simple calls without type variables

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/ConeInferenceContext.kt

@@ -256,7 +256,7 @@ interface ConeInferenceContext : TypeSystemInferenceExtensionContext,
     }
 
     override fun typeSubstitutorByTypeConstructor(map: Map<TypeConstructorMarker, KotlinTypeMarker>): TypeSubstitutorMarker {
-        if (map.isEmpty()) return ConeSubstitutor.Empty
+        if (map.isEmpty()) return createEmptySubstitutor()
         return object : AbstractConeSubstitutor(),
             TypeSubstitutorMarker {
             override fun substituteType(type: ConeKotlinType): ConeKotlinType? {
@@ -266,6 +266,10 @@ interface ConeInferenceContext : TypeSystemInferenceExtensionContext,
         }
     }
 
+    override fun createEmptySubstitutor(): TypeSubstitutorMarker {
+        return ConeSubstitutor.Empty
+    }
+
     override fun TypeSubstitutorMarker.safeSubstitute(type: KotlinTypeMarker): KotlinTypeMarker {
         if (this === NoSubstitutor) return type
         require(this is ConeSubstitutor)

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/FirCallCompleter.kt

@@ -27,6 +27,7 @@ import org.jetbrains.kotlin.fir.types.impl.FirResolvedTypeRefImpl
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.calls.components.InferenceSession
 import org.jetbrains.kotlin.resolve.calls.inference.buildAbstractResultingSubstitutor
+import org.jetbrains.kotlin.resolve.calls.inference.components.EmptySubstitutor
 import org.jetbrains.kotlin.resolve.calls.inference.components.KotlinConstraintSystemCompleter
 import org.jetbrains.kotlin.resolve.calls.inference.model.SimpleConstraintSystemConstraintPosition
 import org.jetbrains.kotlin.types.model.StubTypeMarker