SI-8325 Accept infix star type outside patterns

This is a follow-up to SI-5702 which enabled use of
`*` in infix notation in patterns.

Most of the work is in distinguishing infix from a
sequence pattern.

Also, do not take backticked star as the repeated
parameter marker in postfix position. That is,
`Int``*``` is not `Int*` -- I hope double-tick
renders as tick. There is not a special use case
except that backticks mean "I am an identifier, as
is, and not a keyword."

1 files changed, 7 insertions, 0 deletions

diff --git a/test/files/neg/t8325-c.check b/test/files/neg/t8325-c.check
new file mode 100644
index 0000000000..51ea4988a6
--- /dev/null
+++ b/test/files/neg/t8325-c.check
@@ -0,0 +1,7 @@
+t8325-c.scala:3: error: identifier expected but ')' found.
+  def k(xx: Int`*`) = ???
+                  ^
+t8325-c.scala:4: error: ')' expected but '}' found.
+}
+^
+two errors found