[FIR TEST] Add test with MutableMap.compute

compiler/fir/resolve/testData/resolve/stdlib/j+k/MapCompute.kt

@@ -0,0 +1,11 @@
+// FULL_JDK
+// STDLIB_JDK8
+// !JVM_TARGET: 1.8
+
+fun <D> MutableMap<String, MutableSet<D>>.initAndAdd(key: String, value: D) {
+    this.<!UNRESOLVED_REFERENCE!>compute<!>(key) { _, maybeValues ->
+        val setOfValues = maybeValues ?: mutableSetOf()
+        setOfValues.<!UNRESOLVED_REFERENCE!>add<!>(value)
+        setOfValues
+    }
+}

compiler/fir/resolve/testData/resolve/stdlib/j+k/MapCompute.txt

@@ -0,0 +1,17 @@
+FILE: MapCompute.kt
+    public final fun <D> R|kotlin/collections/MutableMap<kotlin/String, kotlin/collections/MutableSet<D>>|.initAndAdd(key: R|kotlin/String|, value: R|D|): R|kotlin/Unit| {
+        this@R|/initAndAdd|.<Unresolved name: compute>#(R|<local>/key|, <L> = compute@fun <anonymous>(_: R|ERROR CLASS: No type for parameter|, maybeValues: R|ERROR CLASS: No type for parameter|): R|ERROR CLASS: Unresolved: <error>| {
+            lval setOfValues: R|ERROR CLASS: Unresolved: <error>| = when (lval <elvis>: R|ERROR CLASS: No type for parameter| = R|<local>/maybeValues|) {
+                ==($subj$, Null(null)) ->  {
+                    R|kotlin/collections/mutableSetOf|<R|kotlin/Any?|>()
+                }
+                else ->  {
+                    R|<local>/<elvis>|
+                }
+            }
+
+            R|<local>/setOfValues|.<Unresolved name: add>#(R|<local>/value|)
+            ^ R|<local>/setOfValues|
+        }
+        )
+    }

compiler/fir/resolve/tests/org/jetbrains/kotlin/fir/FirDiagnosticsWithStdlibTestGenerated.java

@@ -544,6 +544,11 @@ public class FirDiagnosticsWithStdlibTestGenerated extends AbstractFirDiagnostic
             runTest("compiler/fir/resolve/testData/resolve/stdlib/j+k/LoggerInstance.kt");
         }
 
+        @TestMetadata("MapCompute.kt")
+        public void testMapCompute() throws Exception {
+            runTest("compiler/fir/resolve/testData/resolve/stdlib/j+k/MapCompute.kt");
+        }
+
         @TestMetadata("MapEntry.kt")
         public void testMapEntry() throws Exception {
             runTest("compiler/fir/resolve/testData/resolve/stdlib/j+k/MapEntry.kt");