Transform builtin Map declaration and adjust stdlib

compiler/testData/diagnostics/tests/j+k/collectionOverrides/mapGetOverride.kt

@@ -0,0 +1,13 @@
+// !DIAGNOSTICS: -UNUSED_VALUE -ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE
+// FILE: MyMap.java
+
+abstract public class MyMap extends java.util.AbstractMap<Double, CharSequence> {
+    String get(Object q) { }
+}
+
+// FILE: main.kt
+
+fun foo(m: MyMap) {
+    var x: String? = m.get(1.0)
+    x = m[2.0]
+}