Restore original accessor signature as deprecated

The deprecated function is not operator because it covers cases where it was used in explicit form.

#KT-18789

libraries/stdlib/src/kotlin/collections/MapAccessors.kt

@@ -29,6 +29,13 @@ public inline operator fun <V, V1: V> Map<in String, @Exact V>.getValue(thisRef:
 public inline operator fun <V, V1: V> MutableMap<in String, out @Exact V>.getValue(thisRef: Any?, property: KProperty<*>): V1
         = @Suppress("UNCHECKED_CAST") (getOrImplicitDefault(property.name) as V1)
 
+@Deprecated("Use getValue() with two type parameters instead")
+@kotlin.jvm.JvmName("getVarContravariant")
+@kotlin.internal.LowPriorityInOverloadResolution
+@kotlin.internal.InlineOnly
+public inline fun <V> MutableMap<in String, in V>.getValue(thisRef: Any?, property: KProperty<*>): V
+        = @Suppress("UNCHECKED_CAST") (getOrImplicitDefault(property.name) as V)
+
 /**
  * Stores the value of the property for the given object in this mutable map.
  * @param thisRef the object for which the value is requested (not used).

libraries/stdlib/test/properties/delegation/MapAccessorsTest.kt

@@ -63,4 +63,15 @@ class VarByMapExtensionsTest {
         map["d"] = null
         assertEquals(null, d)
     }
+
+    @Test fun deprecatedAccessors() {
+        assertEquals<Int>(
+                expected = map.getValue(this, VarByMapExtensionsTest::c),
+                actual = map.getValue<Int>(this, VarByMapExtensionsTest::c)
+        )
+        assertEquals<String>(
+                expected = map2.getValue<CharSequence, String>(this, VarByMapExtensionsTest::a2),
+                actual = map2.getValue<String>(this, VarByMapExtensionsTest::a2)
+        )
+    }
 }