Fix resolver for compiler bridge

I noticed that we can't resolve the compiler bridge out of snapshot repo.

main-settings/src/main/scala/sbt/SlashSyntax.scala

@@ -88,3 +88,5 @@ object SlashSyntax {
   final class RichScope(protected val scope: Scope) extends HasSlashKey
 
 }
+
+private[sbt] object SlashSyntax0 extends SlashSyntax

main/src/main/scala/sbt/Defaults.scala

@@ -107,6 +107,7 @@ import sbt.internal.inc.{
   MixedAnalyzingCompiler,
   ScalaInstance
 }
+import sbt.SlashSyntax0._
 
 object Defaults extends BuildCommon {
   final val CacheDirectoryName = "cache"
@@ -518,7 +519,7 @@ object Defaults extends BuildCommon {
               globalLock = launcher.globalLock,
               componentProvider = app.provider.components,
               secondaryCacheDir = Option(zincDir),
-              dependencyResolution = dependencyResolution.value,
+              dependencyResolution = bootDependencyResolution.value,
               compilerBridgeSource = scalaCompilerBridgeSource.value,
               scalaJarsTarget = zincDir,
               log = streams.value.log
@@ -2361,7 +2362,10 @@ object Classpaths {
             }
           } tag (Tags.Update, Tags.Network)).value
         )
-      ) ++ Seq(bootIvyConfiguration := (ivyConfiguration in updateSbtClassifiers).value)
+      ) ++ Seq(
+      bootIvyConfiguration := (updateSbtClassifiers / ivyConfiguration).value,
+      bootDependencyResolution := (updateSbtClassifiers / dependencyResolution).value
+    )
 
   def classifiersModuleTask: Initialize[Task[GetClassifiersModule]] =
     Def.task {

main/src/main/scala/sbt/Keys.scala

@@ -360,6 +360,7 @@ object Keys {
   val ivyConfigurations = settingKey[Seq[Configuration]]("The defined configurations for dependency management.  This may be different from the configurations for Project settings.").withRank(BSetting)
   // This setting was created to work around the limitation of derived tasks not being able to use task-scoped task: ivyConfiguration in updateSbtClassifiers
   val bootIvyConfiguration = taskKey[IvyConfiguration]("General dependency management (Ivy) settings, configured to retrieve sbt's components.").withRank(DTask)
+  val bootDependencyResolution = taskKey[DependencyResolution]("Dependency resolution to retrieve sbt's components.").withRank(CTask)
   val moduleSettings = taskKey[ModuleSettings]("Module settings, which configure dependency management for a specific module, such as a project.").withRank(DTask)
   val unmanagedBase = settingKey[File]("The default directory for manually managed libraries.").withRank(ASetting)
   val updateConfiguration = settingKey[UpdateConfiguration]("Configuration for resolving and retrieving managed dependencies.").withRank(DSetting)