break tabwriter columns when starting a new block of indented statements

R=r
DELTA=16  (15 added, 0 deleted, 1 changed)
OCL=32475
CL=32481

src/pkg/go/printer/printer.go

@@ -681,7 +681,7 @@ func (p *printer) decl(decl ast.Decl) (comment *ast.CommentGroup, optSemi bool)
 // Print the statement list indented, but without a newline after the last statement.
 func (p *printer) stmtList(list []ast.Stmt) {
 	if len(list) > 0 {
-		p.print(+1, newline);
+		p.print(+1, formfeed);  // the next lines have different structure
 		optSemi := false;
 		for i, s := range list {
 			if i > 0 {

src/pkg/go/printer/testdata/golden1.go

@@ -50,3 +50,10 @@ func f1() {
 	/* 4 */
 	f0()
 }
+
+func abs(x int) int {
+	if x < 0 {	// the tab printed before this comment's // must not affect the remaining lines
+		return -x	// this statement should be properly indented
+	}
+	return x
+}

src/pkg/go/printer/testdata/source1.go

@@ -50,3 +50,11 @@ func f1() {
 	/* 4 */
 	f0();
 }
+
+
+func abs(x int) int {
+	if x < 0 {  // the tab printed before this comment's // must not affect the remaining lines
+		return -x;  // this statement should be properly indented
+	}
+	return x;
+}