Don't return unimportables from importedSymbol.

Hardening against the symptom of SI-6745, which yielded:

   wat.scala:4: error: too many arguments for constructor Predef: ()object Predef
      def this() = this(0)
               ^
The fix for the underlying problem in that bug
has been targetted at branch 2.10.x.

1 files changed, 22 insertions, 0 deletions

diff --git a/test/files/run/t6745-2.scala b/test/files/run/t6745-2.scala
new file mode 100644
index 0000000000..31ecd42bd1
--- /dev/null
+++ b/test/files/run/t6745-2.scala
@@ -0,0 +1,22 @@
+import scala.tools.nsc._
+import scala.tools.partest.CompilerTest
+import scala.collection.{ mutable, immutable, generic }
+
+object Test extends CompilerTest {
+  import global._
+  import rootMirror._
+  import definitions._
+  import global.analyzer.{Context, ImportInfo}
+
+  override def code = """
+package context {
+}
+  """
+
+  def check(source: String, unit: global.CompilationUnit) = {
+    val context: Context = global.analyzer.rootContext(unit)
+    val importInfo: ImportInfo = context.imports.head // Predef._
+    val importedSym = importInfo.importedSymbol(nme.CONSTRUCTOR)
+    assert(importedSym == NoSymbol, importedSym) // was "constructor Predef"
+  }
+}