[fs] BigIntStats should use js.BigInt & Remove ~Ns fron nodejs-v10

app/nodejs-v10/src/test/scala/io/scalajs/nodejs/fs/FsTest.scala

@@ -115,5 +115,17 @@ class FsTest extends AsyncFunSpec {
         succeed
       }
     }
+
+    it("support double stats") {
+      Fs.statFuture("./package.json").map { stats =>
+        assert(stats.birthtimeMs.toLong > 0L)
+      }
+    }
+
+    it("support bigint stats") {
+      Fs.statFuture("./package.json", StatOptions(bigint = true)).map { stats =>
+        assert(stats.asInstanceOf[BigIntStats].birthtimeMs.toString.toLong > 0L)
+      }
+    }
   }
 }

app/nodejs-v12/src/test/scala/io/scalajs/nodejs/fs/FsClassesTest.scala

@@ -31,4 +31,12 @@ class FsClassesTest extends AnyFunSpec {
       assert(ex.getMessage().contains("ERR_DIR_CLOSED"))
     }
   }
+
+  it("adds new members on bigint stats") {
+    val stats = Fs.statSync("./package.json", StatOptions(bigint = true)).asInstanceOf[BigIntStats]
+    assert(stats.asInstanceOf[BigIntStats].birthtimeNs.toString.toLong > 0L)
+    assert(stats.asInstanceOf[BigIntStats].ctimeNs.toString.toLong > 0L)
+    assert(stats.asInstanceOf[BigIntStats].atimeNs.toString.toLong > 0L)
+    assert(stats.asInstanceOf[BigIntStats].mtimeNs.toString.toLong > 0L)
+  }
 }

app/nodejs-v14/src/main/scala/io/scalajs/nodejs/fs/Stats.scala

@@ -1,6 +1,8 @@
 package io.scalajs.nodejs
 package fs
 
+import com.thoughtworks.enableIf
+
 import scala.scalajs.js
 
 @js.native
@@ -142,9 +144,16 @@ trait Stats extends IStats[Int, Double]
   * @since 0.1.21
   */
 @js.native
-trait BigIntStats extends IStats[BigInt, BigInt] {
-  def atimeNs: BigInt     = js.native
-  def mtimeNs: BigInt     = js.native
-  def ctimeNs: BigInt     = js.native
-  def birthtimeNs: BigInt = js.native
+trait BigIntStats extends IStats[js.BigInt, js.BigInt] {
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
+  def atimeNs: js.BigInt = js.native
+
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
+  def mtimeNs: js.BigInt = js.native
+
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
+  def ctimeNs: js.BigInt = js.native
+
+  @enableIf(io.scalajs.nodejs.internal.CompilerSwitches.gteNodeJs12)
+  def birthtimeNs: js.BigInt = js.native
 }