Revert "go/parser: include more comments in a struct or interface"

This reverts commit https://golang.org/cl/161177/.

Reason for revert: this led to non-contiguous comments spaced
by an empty line to be grouped into a single CommentGroup

Fixes #32944
Updates #10858

Change-Id: I5e16663b308c3b560496da8e66c33befdf9ed9dd
Reviewed-on: https://go-review.googlesource.com/c/go/+/185040
Reviewed-by: Robert Griesemer <[email protected]>

Author: agnivade

src/go/doc/testdata/issue10858.0.golden

@@ -63,7 +63,6 @@ type parser struct {
 	topScope   *ast.Scope        // top-most scope; may be pkgScope
 	unresolved []*ast.Ident      // unresolved identifiers
 	imports    []*ast.ImportSpec // list of imports
-	inStruct   bool              // if set, parser is parsing a struct or interface (for comment collection)
 
 	// Label scopes
 	// (maintained by open/close LabelScope)
@@ -338,15 +337,7 @@ func (p *parser) next() {
 		// consume successor comments, if any
 		endline = -1
 		for p.tok == token.COMMENT {
-			n := 1
-			// When inside a struct (or interface), we don't want to lose comments
-			// separated from individual field (or method) documentation by empty
-			// lines. Allow for some white space in this case and collect those
-			// comments as a group. See issue #10858 for details.
-			if p.inStruct {
-				n = 2
-			}
-			comment, endline = p.consumeCommentGroup(n)
+			comment, endline = p.consumeCommentGroup(1)
 		}
 
 		if endline+1 == p.file.Line(p.pos) {
@@ -757,7 +748,6 @@ func (p *parser) parseStructType() *ast.StructType {
 	}
 
 	pos := p.expect(token.STRUCT)
-	p.inStruct = true
 	lbrace := p.expect(token.LBRACE)
 	scope := ast.NewScope(nil) // struct scope
 	var list []*ast.Field
@@ -768,7 +758,6 @@ func (p *parser) parseStructType() *ast.StructType {
 		list = append(list, p.parseFieldDecl(scope))
 	}
 	rbrace := p.expect(token.RBRACE)
-	p.inStruct = false
 
 	return &ast.StructType{
 		Struct: pos,
@@ -970,15 +959,13 @@ func (p *parser) parseInterfaceType() *ast.InterfaceType {
 	}
 
 	pos := p.expect(token.INTERFACE)
-	p.inStruct = true
 	lbrace := p.expect(token.LBRACE)
 	scope := ast.NewScope(nil) // interface scope
 	var list []*ast.Field
 	for p.tok == token.IDENT {
 		list = append(list, p.parseMethodSpec(scope))
 	}
 	rbrace := p.expect(token.RBRACE)
-	p.inStruct = false
 
 	return &ast.InterfaceType{
 		Interface: pos,