Bug 1565129 - Re-introduce plain_text.wrap_long_lines. r=bzbarsky

Looks like some users use it, and it's not too much effort to support. This is
somewhat simpler, and IMO better than what existed before bug 1514655 because:

 * It doesn't regress bidi rendering when the pref is disabled (before, the pref
   would prevent plaintext.css from applying altogether).

 * It's consistent with the way view-source docs work.

 * It doesn't use non-standard stylesheet APIs to toggle the stylesheet
   (bug 1260720).

Differential Revision: https://phabricator.services.mozilla.com/D37742

--HG--
extra : moz-landing-system : lando

layout/reftests/bugs/1565129.txt

@@ -0,0 +1 @@
+Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text. Some very very long text.

layout/reftests/bugs/reftest.list

@@ -2114,3 +2114,4 @@ skip-if(!asyncPan) == 1544895.html 1544895-ref.html
 == 1563484.html 1563484-ref.html
 fuzzy-if(!webrender||!winWidget,254-255,464-1613) fuzzy-if(geckoview&&webrender,253-253,1397-1397) == 1562733-rotated-nastaliq-1.html 1562733-rotated-nastaliq-1-ref.html
 == 1562733-rotated-nastaliq-2.html 1562733-rotated-nastaliq-2-ref.html
+test-pref(plain_text.wrap_long_lines,false) != 1565129.txt 1565129.txt

layout/style/res/plaintext.css

@@ -8,6 +8,10 @@ pre {
   -moz-control-character-visibility: visible;
 }
 
+.nowrap pre {
+  white-space: pre;
+}
+
 /* Make text go with the rules of dir=auto, but allow it to be overriden if 'Switch Text Direction' is triggered */
 html:not([dir]) pre { /* Not a UA sheet, so doesn't use :-moz-has-dir-attr */
   unicode-bidi: plaintext;

modules/libpref/init/StaticPrefList.h

@@ -6978,6 +6978,18 @@ VARCACHE_PREF(
   RelaxedAtomicBool, false
 )
 
+//---------------------------------------------------------------------------
+// Prefs starting with "plain_text."
+//---------------------------------------------------------------------------
+
+// When false, text in plaintext documents does not wrap long lines.
+VARCACHE_PREF(
+  Live,
+  "plain_text.wrap_long_lines",
+  plain_text_wrap_long_lines,
+  bool, true
+)
+
 //---------------------------------------------------------------------------
 // Prefs starting with "plugins."
 //---------------------------------------------------------------------------

parser/html/nsHtml5PlainTextUtils.cpp

@@ -3,12 +3,11 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "nsHtml5PlainTextUtils.h"
-#include "mozilla/Preferences.h"
+#include "mozilla/StaticPrefs.h"
 #include "nsHtml5AttributeName.h"
 #include "nsHtml5Portability.h"
 #include "nsHtml5String.h"
-#include "nsIServiceManager.h"
-#include "nsIStringBundle.h"
+#include "nsGkAtoms.h"
 
 // static
 nsHtml5HtmlAttributes* nsHtml5PlainTextUtils::NewLinkAttributes() {
@@ -20,3 +19,14 @@ nsHtml5HtmlAttributes* nsHtml5PlainTextUtils::NewLinkAttributes() {
   linkAttrs->addAttribute(nsHtml5AttributeName::ATTR_HREF, href, -1);
   return linkAttrs;
 }
+
+// static
+nsHtml5HtmlAttributes* nsHtml5PlainTextUtils::NewBodyAttributes() {
+  nsHtml5HtmlAttributes* bodyAttrs = new nsHtml5HtmlAttributes(0);
+  if (!mozilla::StaticPrefs::plain_text_wrap_long_lines()) {
+    RefPtr<nsAtom> nowrap = nsGkAtoms::nowrap;
+    bodyAttrs->addAttribute(nsHtml5AttributeName::ATTR_CLASS,
+                            nsHtml5String::FromAtom(nowrap.forget()), -1);
+  }
+  return bodyAttrs;
+}

parser/html/nsHtml5PlainTextUtils.h

@@ -10,6 +10,7 @@
 class nsHtml5PlainTextUtils {
  public:
   static nsHtml5HtmlAttributes* NewLinkAttributes();
+  static nsHtml5HtmlAttributes* NewBodyAttributes();
 };
 
 #endif  // nsHtml5PlainTextUtils_h

parser/html/nsHtml5TreeBuilderCppSupplement.h

@@ -1276,6 +1276,9 @@ void nsHtml5TreeBuilder::StartPlainText() {
   startTag(nsHtml5ElementName::ELT_LINK,
            nsHtml5PlainTextUtils::NewLinkAttributes(), false);
 
+  startTag(nsHtml5ElementName::ELT_BODY,
+           nsHtml5PlainTextUtils::NewBodyAttributes(), false);
+
   StartPlainTextBody();
 }