Add test for dotc.core pickling/unpickling

Author: VladimirNik

test/dotc/tests.scala

@@ -230,6 +230,7 @@ class tests extends CompilerTest {
   @Test def tasty_dotc_printing = compileDir(dotcDir, "printing", testPickling)
   @Test def tasty_dotc_reporting = compileDir(dotcDir, "reporting", testPickling)
   @Test def tasty_dotc_util = compileDir(dotcDir, "util", testPickling)
+  @Test def tasty_core = compileDir(dotcDir, "core", testPickling, xerrors = 1)
   @Test def tasty_tools_io = compileDir(toolsDir, "io", testPickling)
   @Test def tasty_tests = compileDir(testsDir, "tasty", testPickling)
 }