Annotate & test j.u.f.BiPredicate default methods.

This PR builds upon merged PR scala-native#1937 by annotating the existing
j.u.f.BiPredicate.scala and porting its corresponding BiPredicateTest
from Scala.js.

The existing file was edited rather than porting the most current
Scala.js commit because the latter uses lambdas and those
do not play well when using Scala Native with Scala 2.11.

See Issue scala-native#1972 for background & discussion of JavaDefaultMethod
annotation.

javalib/src/main/scala/java/util/function/BiPredicate.scala

@@ -1,23 +1,30 @@
+// Influenced by Scala.js commit: 0c27b64 dated: 2020-09-06
+
 package java.util.function
 
+import scala.scalanative.annotation.JavaDefaultMethod
+
 trait BiPredicate[T, U] { self =>
+  def test(t: T, u: U): Boolean
+
+  @JavaDefaultMethod
   def and(other: BiPredicate[_ >: T, _ >: U]): BiPredicate[T, U] =
     new BiPredicate[T, U] {
       override def test(t: T, u: U): Boolean =
         self.test(t, u) && other.test(t, u)
     }
 
+  @JavaDefaultMethod
   def negate(): BiPredicate[T, U] =
     new BiPredicate[T, U] {
       override def test(t: T, u: U): Boolean =
         !self.test(t, u)
     }
 
+  @JavaDefaultMethod
   def or(other: BiPredicate[_ >: T, _ >: U]): BiPredicate[T, U] =
     new BiPredicate[T, U] {
       override def test(t: T, u: U): Boolean =
         self.test(t, u) || other.test(t, u)
     }
-
-  def test(t: T, u: U): Boolean
 }