Add pending scripted test for Ant-style compilation.

Add pending test for Ant-style incremental compilation. In that mode
incremental compiler will recompile only the source files that were changed
by the user and won't try to invalidate any dependencies.

Once Ant-style incremental compilation is implemented this test should be
passing.

sbt/src/sbt-test/compiler-project/inc-ant-style/build.sbt

@@ -0,0 +1,28 @@
+logLevel := Level.Debug
+
+incOptions := incOptions.value.withNameHashing(true)
+
+/* Performs checks related to compilations:
+ *  a) checks in which compilation given set of files was recompiled
+ *  b) checks overall number of compilations performed
+ */
+TaskKey[Unit]("check-compilations") <<= (compile in Compile, scalaSource in Compile) map { (a: sbt.inc.Analysis, src: java.io.File) =>
+  def relative(f: java.io.File): java.io.File =  f.relativeTo(src) getOrElse f
+  val allCompilations = a.compilations.allCompilations
+  val recompiledFiles: Seq[Set[java.io.File]] = allCompilations map { c =>
+    val recompiledFiles = a.apis.internal.collect {
+      case (file, api) if api.compilation.startTime == c.startTime => relative(file)
+    }
+    recompiledFiles.toSet
+  }
+  def recompiledFilesInIteration(iteration: Int, fileNames: Set[String]) = {
+    val files = fileNames.map(new java.io.File(_))
+    assert(recompiledFiles(iteration) == files, "%s != %s".format(recompiledFiles(iteration), files))
+  }
+  assert(allCompilations.size == 2)
+  // B.scala and C.scala are compiled at the beginning, in the Ant-style incremental compilation
+  // they are not rebuild when A.scala.
+  recompiledFilesInIteration(0, Set("B.scala", "C.scala"))
+  // A.scala is changed and recompiled
+  recompiledFilesInIteration(1, Set("A.scala"))
+}

sbt/src/sbt-test/compiler-project/inc-ant-style/changes/A1.scala

@@ -0,0 +1,3 @@
+package test3
+
+trait A

sbt/src/sbt-test/compiler-project/inc-ant-style/pending

@@ -0,0 +1,9 @@
+# introduces first compile iteration
+> compile
+# this change is local to method and does not change api so introduces
+# only one additional compile iteration
+$ copy-file changes/A1.scala src/main/scala/A.scala
+# second iteration
+> compile
+# check if there are only two compile iterations performed
+> check-compilations

sbt/src/sbt-test/compiler-project/inc-ant-style/src/main/scala/A.scala

@@ -0,0 +1,5 @@
+package test3
+
+trait A {
+  def foo = 1
+}

sbt/src/sbt-test/compiler-project/inc-ant-style/src/main/scala/B.scala

@@ -0,0 +1,3 @@
+package test3
+
+trait B extends A

sbt/src/sbt-test/compiler-project/inc-ant-style/src/main/scala/C.scala

@@ -0,0 +1,5 @@
+package test3
+
+trait C {
+  def abc(a: A): Int = a.foo
+}