ASSERTION FAILED: !m_overflow

third_party/WebKit/Source/core/layout/line/InlineBox.h

Index: third_party/WebKit/Source/core/layout/line/InlineBox.h
diff --git a/third_party/WebKit/Source/core/layout/line/InlineBox.h b/third_party/WebKit/Source/core/layout/line/InlineBox.h
index dedadf41a79901c3a6e0a5fbc0c7bcdc163b3345..8e2cdd62f618efcf011d74d2a38d306675229a92 100644
--- a/third_party/WebKit/Source/core/layout/line/InlineBox.h
+++ b/third_party/WebKit/Source/core/layout/line/InlineBox.h
@@ -351,6 +351,14 @@ public:
         ADD_BOOLEAN_BITFIELD(endsWithBreak, EndsWithBreak); // Whether the line ends with a <br>.
         // shared between RootInlineBox and InlineTextBox
         ADD_BOOLEAN_BITFIELD(hasSelectedChildrenOrCanHaveLeadingExpansion, HasSelectedChildrenOrCanHaveLeadingExpansion);
+
+        // This boolean tracks whether we know this box to have no overflow.

[leviw_travelin_and_unemployed, 2015/11/10 20:23:22]

"whether we know this box has no overflow"

[Julien - ping for review, 2015/11/10 23:52:47]

Changed.

+        //
+        // Note that this boolean shouldn't be set if we could have overflow.

[leviw_travelin_and_unemployed, 2015/11/10 20:23:22]

I don't feel that the middle 2 lines of this comment are useful.

[Julien - ping for review, 2015/11/10 23:52:47]

I strongly think they are (or at least something similar). When looking at the
boolean's lifecycle, it downed on me that it's never reset if it's ever cleared.
Those lines are meant to clarify this: it's a _conservative_ estimation and we
do allow some type of errors.

[leviw_travelin_and_unemployed, 2015/11/12 22:57:51]

Can you explain to me how "tracks whether we know this box has no overflow" and
that it "shouldn't be set if we could have overflow" add different information?

[Julien - ping for review, 2015/11/13 00:31:32]

Fair point, amended the comment to avoid this duplication:

// This boolean will never be set if there is potential for overflow,
// but it will be eagerly cleared in the opposite case. As such, it's
// a conservative tracking of the absence of overflow.

+        // As such, it's a conservative tracking of the absence of overflow.
+        //
+        // For whether we have overflow, callers should use m_overflow on
+        // InlineFlowBox.
         ADD_BOOLEAN_BITFIELD(knownToHaveNoOverflow, KnownToHaveNoOverflow);
         ADD_BOOLEAN_BITFIELD(hasEllipsisBoxOrHyphen, HasEllipsisBoxOrHyphen);
         // for InlineTextBox