Add errors for bougs $!x and $.x parameter use.

Catch $.x usage in a submethod, plus catch sub ($!x) { } even when
the sub is inside of a class. This took a bit more doing than first
expected, since 'has ($.x, $.y)' is also parsed using a signature.

src/Perl6/Actions.nqp

@@ -4011,7 +4011,10 @@ Compilation unit '$file' contained the following violations:
                 }
             }
             elsif $twigil eq '!' {
-                %*PARAM_INFO<bind_attr>    := 1;
+                if !$*HAS_SELF && $*SURROUNDING_DECL ne 'variable' {
+                    $*W.throw($/, ['X', 'Syntax', 'NoSelf'], variable => ~$/);
+                }
+                %*PARAM_INFO<bind_attr> := 1;
                 my int $succ := 1;
                 try {
                     %*PARAM_INFO<attr_package> := $*W.find_symbol(['$?CLASS']);
@@ -4024,6 +4027,14 @@ Compilation unit '$file' contained the following violations:
                 }
             }
             elsif $twigil eq '.' {
+                if $*SURROUNDING_DECL ne 'variable' {
+                    if !$*HAS_SELF {
+                        $*W.throw($/, ['X', 'Syntax', 'NoSelf'], variable => ~$/);
+                    }
+                    elsif $*HAS_SELF eq 'partial' {
+                        $*W.throw($/, ['X', 'Syntax', 'VirtualCall'], call => ~$/);
+                    }
+                }
                 %*PARAM_INFO<bind_accessor> := 1;
                 if $<name> {
                     %*PARAM_INFO<variable_name> := ~$<name>;

src/Perl6/Grammar.nqp

@@ -2237,7 +2237,7 @@ grammar Perl6::Grammar is HLL::Grammar does STD {
           || <?{ $*SCOPE eq 'has' }> <.newpad> [ <.ws> <initializer> ]? { $*ATTR_INIT_BLOCK := $*W.pop_lexpad() }
           || [ <.ws> <initializer> ]?
           ]
-        | '(' ~ ')' <signature> [ <.ws> <trait>+ ]? [ <.ws> <initializer> ]?
+        | '(' ~ ')' <signature('variable')> [ <.ws> <trait>+ ]? [ <.ws> <initializer> ]?
         | <routine_declarator>
         | <regex_declarator>
         | <type_declarator>
@@ -2615,8 +2615,7 @@ grammar Perl6::Grammar is HLL::Grammar does STD {
         <signature>
     }
 
-    token signature {
-        :my $*IN_DECL := 'sig';
+    token signature($*IN_DECL = 'sig') {
         :my $*zone := 'posreq';
         :my $*multi_invocant := 1;
         :my @*seps := nqp::list();
@@ -2713,6 +2712,7 @@ grammar Perl6::Grammar is HLL::Grammar does STD {
         :dba('formal parameter')
         :my $*DOC := $*DECLARATOR_DOCS; # these get cleared later
         :my $*POD_BLOCK;
+        :my $*SURROUNDING_DECL := nqp::getlexdyn('$*IN_DECL');
         <.attach_leading_docs>
         {
             my $line_no := HLL::Compiler.lineof(self.orig(), self.from(), :cache(1));