Bug 607857. If caret is in a frame that needs reflow we can wrongly position the caret rect. r=roc a=blocking-final

layout/base/nsCaret.cpp

@@ -357,14 +357,17 @@ void nsCaret::SetCaretReadOnly(PRBool inMakeReadonly)
   mReadOnly = inMakeReadonly;
 }
 
-void
+nsresult
 nsCaret::GetGeometryForFrame(nsIFrame* aFrame,
                              PRInt32   aFrameOffset,
                              nsRect*   aRect,
                              nscoord*  aBidiIndicatorSize)
 {
   nsPoint framePos(0, 0);
-  aFrame->GetPointFromOffset(aFrameOffset, &framePos);
+  nsresult rv = aFrame->GetPointFromOffset(aFrameOffset, &framePos);
+  if (NS_FAILED(rv))
+    return rv;
+
   nsIFrame *frame = aFrame->GetContentInsertionFrame();
   NS_ASSERTION(frame, "We should not be in the middle of reflow");
   nscoord baseline = frame->GetCaretBaseline();
@@ -401,6 +404,8 @@ nsCaret::GetGeometryForFrame(nsIFrame* aFrame,
 
   if (aBidiIndicatorSize)
     *aBidiIndicatorSize = caretMetrics.mBidiIndicatorSize;
+
+  return NS_OK;
 }
 
 nsIFrame* nsCaret::GetGeometry(nsISelection* aSelection, nsRect* aRect,
@@ -1089,7 +1094,11 @@ nsCaret::UpdateCaretRects(nsIFrame* aFrame, PRInt32 aFrameOffset)
   NS_ASSERTION(aFrame, "Should have a frame here");
 
   nscoord bidiIndicatorSize;
-  GetGeometryForFrame(aFrame, aFrameOffset, &mCaretRect, &bidiIndicatorSize);
+  nsresult rv =
+    GetGeometryForFrame(aFrame, aFrameOffset, &mCaretRect, &bidiIndicatorSize);
+  if (NS_FAILED(rv)) {
+    return PR_FALSE;
+  }
 
   // on RTL frames the right edge of mCaretRect must be equal to framePos
   const nsStyleVisibility* vis = aFrame->GetStyleVisibility();

layout/base/nsCaret.h

@@ -217,10 +217,10 @@ protected:
       nscoord mCaretWidth;        // full caret width including bidi indicator
     };
     Metrics ComputeMetrics(nsIFrame* aFrame, PRInt32 aOffset, nscoord aCaretHeight);
-    void GetGeometryForFrame(nsIFrame* aFrame,
-                             PRInt32   aFrameOffset,
-                             nsRect*   aRect,
-                             nscoord*  aBidiIndicatorSize);
+    nsresult GetGeometryForFrame(nsIFrame* aFrame,
+                                 PRInt32   aFrameOffset,
+                                 nsRect*   aRect,
+                                 nscoord*  aBidiIndicatorSize);
 
     // Returns true if the caret should be drawn. When |mDrawn| is true,
     // this returns true, so that we erase the drawn caret. If |aIgnoreDrawnState|