Fix Japanese line breaking rule before and after ruby

Source/core/layout/LayoutRubyRun.cpp

Index: Source/core/layout/LayoutRubyRun.cpp
diff --git a/Source/core/layout/LayoutRubyRun.cpp b/Source/core/layout/LayoutRubyRun.cpp
index 7f8c29ebb40be920c55315f5d75e30c339831768..c5eef9107ffa7b3bcab972459f6d5217ace9be12 100644
--- a/Source/core/layout/LayoutRubyRun.cpp
+++ b/Source/core/layout/LayoutRubyRun.cpp
@@ -302,4 +302,28 @@ void LayoutRubyRun::getOverhang(bool firstLine, LayoutObject* startLayoutObject,
         endOverhang = std::min<int>(endOverhang, std::min<int>(toLayoutText(endLayoutObject)->minLogicalWidth(), halfWidthOfFontSize));
 }
 
+bool LayoutRubyRun::canBreakBefore(const LazyLineBreakIterator& iterator) const
+{
+    // TODO(kojii): It would be nice to improve this so that it isn't just
+    // hard-coded, but lookahead in this case is particularly problematic.

[eae, 2015/08/21 20:47:06]

Could you add a crbug link here?

[kojii, 2015/08/22 03:49:34]

Done.

+
+    if (!iterator.priorContextLength())
+        return true;
+    UChar ch = iterator.lastCharacter();
+    ULineBreak lineBreak = (ULineBreak)u_getIntPropertyValue(ch, UCHAR_LINE_BREAK);

[eae, 2015/08/21 20:47:06]

static_cast

[kojii, 2015/08/22 03:49:34]

Done.

+    // UNICODE LINE BREAKING ALGORITHM
+    // http://www.unicode.org/reports/tr14/
+    // And Requirements for Japanese Text Layout, 3.1.7 Characters Not Starting a Line
+    // http://www.w3.org/TR/2012/NOTE-jlreq-20120403/#characters_not_starting_a_line
+    switch (lineBreak) {
+    case U_LB_WORD_JOINER:
+    case U_LB_GLUE:
+    case U_LB_OPEN_PUNCTUATION:
+        return false;
+    default:
+        break;
+    }
+    return true;
+}
+
 } // namespace blink