tests: Update box tests (1050294:id)

backend.native/tests/external/codegen/box/boxingOptimization/explicitEqualsOnDouble.kt

@@ -0,0 +1,8 @@
+// IGNORE_BACKEND: JS
+
+fun equals1(a: Double, b: Double) = a.equals(b)
+
+fun box(): String {
+    if ((-0.0).equals(0.0)) return "fail 0"
+    return "OK"
+}

backend.native/tests/external/codegen/box/boxingOptimization/kt15871.kt

@@ -0,0 +1,5 @@
+fun box() =
+        if (getAndCheck({ 42 }, { 42 })) "OK" else "fail"
+
+inline fun <T> getAndCheck(getFirst: () -> T, getSecond: () -> T) =
+        getFirst() == getSecond()