Jesse Ruderman Reporter
	Description • 11 years ago

      No description provided.

	Jesse Ruderman Reporter
	Comment 2 • 11 years ago

Nightly: bp-c374b5a3-803b-4dc9-a7fb-ab70a2131213

	Mats Palmgren (inactive) Assignee
	Comment 3 • 11 years ago

(gdb) list
91        while (i-- > 0) {
92          nsIFrame* f = oldSSC->mFrames[i];
93          StickyScrollContainer* newSSC = GetStickyScrollContainerForFrame(f);
94          if (newSSC != oldSSC) {
95            oldSSC->RemoveFrame(f);
96            newSSC->AddFrame(f);
97          }
98        }
99      }
100
(gdb) p newSSC
$4 = (mozilla::StickyScrollContainer *) 0x0
(gdb) fr 5
#5 in nsCSSFrameConstructor::ConstructFieldSetFrame ... nsCSSFrameConstructor.cpp:3102
3102            StickyScrollContainer::NotifyReparentedFrameAcrossScrollFrameBoundary(
(gdb) list
3097          // GetAdjustedParentFrame() below depends on this frame order.
3098          childItems.RemoveFrame(child);
3099          // Make sure to reparent the legend so it has the fieldset as the parent.
3100          fieldsetKids.InsertFrame(fieldsetFrame, nullptr, child);
3101          if (scrollFrame) {
3102            StickyScrollContainer::NotifyReparentedFrameAcrossScrollFrameBoundary(
3103                child, blockFrame);
3104          }
3105          break;
3106        }
(gdb) 

I think a simple null-check of 'newSSC' is the right fix.
The frame tree we're building has the fieldset in the fixed list,
so we won't find any scroll frames walking up the ancestors (from legend):

FixedList 0x603000413350 <
  Block(div)(1)@ ... <
    line : <
      FieldSet(fieldset)(1)@ ... <
        Legend(legend)(1)@ next=0x625001867f78 ...<
        >
        HTMLScroll(fieldset)(1)@ ... [sc=0x6250018686c0:-moz-fieldset-content]<
          Block(fieldset)(1)@ [sc=0x625001864428:-moz-scrolled-content]<
          >
        >
      >
    >
  >
>

	Ryan VanderMeulen [:RyanVM]
	Comment 5 • 11 years ago

https://hg.mozilla.org/integration/mozilla-inbound/rev/b3d1f5ab7889

	Ryan VanderMeulen [:RyanVM]
	Comment 6 • 11 years ago

https://hg.mozilla.org/mozilla-central/rev/b3d1f5ab7889