Don't collapse whitespace in contenteditable=plaintext-only.

third_party/WebKit/Source/core/css/resolver/StyleAdjuster.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 213 matching lines @@
     // If we have first-letter pseudo style, transitions, or animations, do not share this style.
     if (style.hasPseudoStyle(PseudoIdFirstLetter) || style.transitions() || style.animations())
         style.setUnique();
 
     // FIXME: when dropping the -webkit prefix on transform-style, we should also have opacity < 1 cause flattening.
     if (style.preserves3D() && (style.overflowX() != OverflowVisible
         || style.overflowY() != OverflowVisible
         || style.hasFilter()))
         style.setTransformStyle3D(TransformStyle3DFlat);
 
+    adjustStyleForEditing(style);
+
     bool isSVGElement = element && element->isSVGElement();
     if (isSVGElement) {
         // Only the root <svg> element in an SVG document fragment tree honors css position
         if (!(isSVGSVGElement(*element) && element->parentNode() && !element->parentNode()->isSVGElement()))
             style.setPosition(ComputedStyle::initialPosition());
 
         // SVG text layout code expects us to be a block-level style element.
         if ((isSVGForeignObjectElement(*element) || isSVGTextElement(*element)) && style.isDisplayInlineType())
             style.setDisplay(BLOCK);
 
         // Columns don't apply to svg text elements.
         if (isSVGTextElement(*element))
             style.clearMultiCol();
     }
     adjustStyleForAlignment(style, parentStyle);
 }
 
+void StyleAdjuster::adjustStyleForEditing(ComputedStyle& style)
+{
+    if (style.userModify() != READ_WRITE_PLAINTEXT_ONLY)
+        return;
+    // Collapsing whitespace is harmful in plain-text editing.
+    if (style.whiteSpace() == NORMAL)
+        style.setWhiteSpace(PRE_WRAP);
+    else if (style.whiteSpace() == NOWRAP)
+        style.setWhiteSpace(PRE);
+    else if (style.whiteSpace() == PRE_LINE)
+        style.setWhiteSpace(PRE_WRAP);
+}
+
 void StyleAdjuster::adjustStyleForFirstLetter(ComputedStyle& style)
 {
     if (style.styleType() != PseudoIdFirstLetter)
         return;
 
     // Force inline display (except for floating first-letters).
     style.setDisplay(style.isFloating() ? BLOCK : INLINE);
 
     // CSS2 says first-letter can't be positioned.
     style.setPosition(StaticPosition);
@@ skipping 175 matching lines @@
         // We want to count vertical percentage paddings/margins on flex items because our current
         // behavior is different from the spec and we want to gather compatibility data.
         if (style.paddingBefore().hasPercent() || style.paddingAfter().hasPercent())
             UseCounter::count(document, UseCounter::FlexboxPercentagePaddingVertical);
         if (style.marginBefore().hasPercent() || style.marginAfter().hasPercent())
             UseCounter::count(document, UseCounter::FlexboxPercentageMarginVertical);
     }
 }
 
 } // namespace blink