go/types: delete unnecessary slice construction

CL 374294 made our check for incorrect type parameters constraints
eager, but failed to remove the construction of the bounds slice, which
was no longer used.

Change-Id: Ib8778fba947ef8a8414803e95d72c49b8f75c204
Reviewed-on: https://go-review.googlesource.com/c/go/+/386717
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

src/cmd/compile/internal/types2/decl.go

@@ -569,7 +569,6 @@ func (check *Checker) collectTypeParams(dst **TypeParamList, list []*syntax.Fiel
 
 	// Keep track of bounds for later validation.
 	var bound Type
-	var bounds []Type
 	for i, f := range list {
 		// Optimization: Re-use the previous type bound if it hasn't changed.
 		// This also preserves the grouped output of type parameter lists
@@ -584,7 +583,6 @@ func (check *Checker) collectTypeParams(dst **TypeParamList, list []*syntax.Fiel
 				check.error(f.Type, "cannot use a type parameter as constraint")
 				bound = Typ[Invalid]
 			}
-			bounds = append(bounds, bound)
 		}
 		tparams[i].bound = bound
 	}

src/go/types/decl.go

@@ -624,7 +624,6 @@ func (check *Checker) collectTypeParams(dst **TypeParamList, list *ast.FieldList
 	}()
 
 	index := 0
-	var bounds []Type
 	for _, f := range list.List {
 		var bound Type
 		// NOTE: we may be able to assert that f.Type != nil here, but this is not
@@ -642,7 +641,6 @@ func (check *Checker) collectTypeParams(dst **TypeParamList, list *ast.FieldList
 		} else {
 			bound = Typ[Invalid]
 		}
-		bounds = append(bounds, bound)
 		for i := range f.Names {
 			tparams[index+i].bound = bound
 		}