tint: intrinsic-gen: Fix parsing of multiple decorations

Change-Id: I61365dea17ab9174cfcb2d513cf1f7ee28ce0647
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/90528
Reviewed-by: David Neto <dneto@google.com>
Commit-Queue: Ben Clayton <bclayton@chromium.org>

tools/src/cmd/intrinsic-gen/parser/parser.go

@@ -154,7 +154,7 @@ func (p *parser) decorations() ast.Decorations {
 			Name:   string(name.Runes),
 			Values: values,
 		})
-		if !p.peekIs(0, tok.Comma) {
+		if p.match(tok.Comma) == nil {
 			break
 		}
 	}

tools/src/cmd/intrinsic-gen/parser/parser_test.go

@@ -90,6 +90,18 @@ func TestParser(t *testing.T) {
 					Name: "T",
 				}},
 			},
+		}, { ///////////////////////////////////////////////////////////////////
+			utils.ThisLine(),
+			"[[deco_a, deco_b]] type T",
+			ast.AST{
+				Types: []ast.TypeDecl{{
+					Decorations: ast.Decorations{
+						{Name: "deco_a", Values: []string{}},
+						{Name: "deco_b", Values: []string{}},
+					},
+					Name: "T",
+				}},
+			},
 		}, { ///////////////////////////////////////////////////////////////////
 			utils.ThisLine(),
 			`[[deco("a", "b")]] type T`, ast.AST{