go/printer: revert "make empty lines break table alignment"

This reverts commit c116265eb3.

The change, while addressing issue #26352, introduced another
regression (#26930), which is worse. Reverting this change in
favor of a better fix for the original issue.

Updates #26352.
Fixes #26930.

Change-Id: I71ad12a8212992cce5c1e73907d1f7460f98d9e8
Reviewed-on: https://go-review.googlesource.com/129255
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/go/printer/nodes.go

@@ -221,22 +221,13 @@ func (p *printer) exprList(prev0 token.Pos, list []ast.Expr, depth int, mode exp
 		// If the previous line and the current line had single-
 		// line-expressions and the key sizes are small or the
 		// ratio between the current key and the geometric mean
-		// does not exceed a threshold, align columns and do not use
-		// formfeed.
-		// If the previous line was an empty line, break the alignment.
-		// (The text/tabwriter will break alignment after an empty line
-		// even if we don't do anything here, but we can't see that; yet
-		// we need to reset the variables used in the geomean
-		// computation after an alignment break. Do it explicitly
-		// instead so we're aware of the break. Was issue #26352.)
+		// if the previous key sizes does not exceed a threshold,
+		// align columns and do not use formfeed.
 		if prevSize > 0 && size > 0 {
 			const smallSize = 40
-			switch {
-			case prevLine+1 < line:
-				useFF = true
-			case count == 0, prevSize <= smallSize && size <= smallSize:
+			if count == 0 || prevSize <= smallSize && size <= smallSize {
 				useFF = false
-			default:
+			} else {
 				const r = 2.5                               // threshold
 				geomean := math.Exp(lnsum / float64(count)) // count > 0
 				ratio := float64(size) / geomean

src/go/printer/testdata/alignment.golden

@@ -128,12 +128,3 @@ func main() {
 		abcdefghijklmnopqrstuvwxyz:		"foo",
 	}
 }
-
-// ----------------------------------------------------------------------------
-// Examples from issue #26352.
-var _ = map[int]string{
-	1:	"",
-
-	12345678901234567890123456789:		"",
-	12345678901234567890123456789012345678:	"",
-}

src/go/printer/testdata/alignment.input

@@ -128,12 +128,3 @@ func main() {
 		abcdefghijklmnopqrstuvwxyz: "foo",
 	}
 }
-
-// ----------------------------------------------------------------------------
-// Examples from issue #26352.
-var _ = map[int]string{
-	1: "",
-
-	12345678901234567890123456789: "",
-	12345678901234567890123456789012345678: "",
-}