Fixes SI-6214.

addSynthetics was calling typedStat that caused flushing error buffer. Typically that would result in errors being re-added but addSynthetics was the last thing to run in typedStats.
Instead of adding yet another check I used this as an opportunity to cleanup the once necessary workaround for typing stats. Since we are now chaining buffers of contexts manual handling is no longer necessary.

Review by @odersky (I recall that you were planning to cleanup that part at some point).

1 files changed, 4 insertions, 0 deletions

diff --git a/test/files/neg/t6214.check b/test/files/neg/t6214.check
new file mode 100644
index 0000000000..6349a3e71c
--- /dev/null
+++ b/test/files/neg/t6214.check
@@ -0,0 +1,4 @@
+t6214.scala:5: error: missing parameter type
+  	m { s => case class Foo() }
+            ^
+one error found