KT-15871 Unnecessary boxing for equality operator on inlined primitive values

Allow kotlin.jvm.internal.Intrinsics#areEqual for boxed values.
Rewrite to primitive equality.

NB we can't do that for Float and Double, because java.lang.Float#equals
and java.lang.Double#equals behave differently from primitive equality comparisons.

js/js.tests/test/org/jetbrains/kotlin/js/test/semantics/JsCodegenBoxTestGenerated.java

@@ -1094,6 +1094,18 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
         }
 
+        @TestMetadata("explicitEqualsOnDouble.kt")
+        public void testExplicitEqualsOnDouble() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/boxingOptimization/explicitEqualsOnDouble.kt");
+            try {
+                doTest(fileName);
+            }
+            catch (Throwable ignore) {
+                return;
+            }
+            throw new AssertionError("Looks like this test can be unmuted. Remove IGNORE_BACKEND directive for that.");
+        }
+
         @TestMetadata("fold.kt")
         public void testFold() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/boxingOptimization/fold.kt");
@@ -1106,6 +1118,12 @@ public class JsCodegenBoxTestGenerated extends AbstractJsCodegenBoxTest {
             doTest(fileName);
         }
 
+        @TestMetadata("kt15871.kt")
+        public void testKt15871() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/boxingOptimization/kt15871.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("kt5493.kt")
         public void testKt5493() throws Exception {
             String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/boxingOptimization/kt5493.kt");