Cache line breaks that are not in the current frame due to bidi resolution. Bug 595435, r=roc, a=blocker

layout/generic/nsTextFrameThebes.cpp

@@ -6396,6 +6396,7 @@ nsTextFrame::ReflowText(nsLineLayout& aLineLayout, nscoord aAvailableWidth,
 
   // Restrict preformatted text to the nearest newline
   PRInt32 newLineOffset = -1; // this will be -1 or a content offset
+  PRInt32 contentNewLineOffset = -1;
   // Pointer to the nsGkAtoms::newline set on this frame's element
   NewlineProperty* cachedNewlineOffset = nsnull;
   if (textStyle->NewlineIsSignificant()) {
@@ -6404,9 +6405,18 @@ nsTextFrame::ReflowText(nsLineLayout& aLineLayout, nscoord aAvailableWidth,
     if (cachedNewlineOffset && cachedNewlineOffset->mStartOffset <= offset &&
         (cachedNewlineOffset->mNewlineOffset == -1 ||
          cachedNewlineOffset->mNewlineOffset >= offset)) {
-      newLineOffset = cachedNewlineOffset->mNewlineOffset;
+      contentNewLineOffset = cachedNewlineOffset->mNewlineOffset;
     } else {
-      newLineOffset = FindChar(frag, offset, length, '\n');
+      contentNewLineOffset = FindChar(frag, offset, 
+                                      mContent->TextLength() - offset, '\n');
+    }
+    if (contentNewLineOffset < offset + length) {
+      /*
+        The new line offset could be outside this frame if the frame has been
+        split by bidi resolution. In that case we won't use it in this reflow
+        (newLineOffset will remain -1), but we will still cache it in mContent
+      */
+      newLineOffset = contentNewLineOffset;
     }
     if (newLineOffset >= 0) {
       length = newLineOffset + 1 - offset;
@@ -6766,7 +6776,8 @@ nsTextFrame::ReflowText(nsLineLayout& aLineLayout, nscoord aAvailableWidth,
   // Updated the cached NewlineProperty, or delete it.
   if (contentLength < maxContentLength &&
       textStyle->NewlineIsSignificant() &&
-      (newLineOffset < 0 || mContentOffset + contentLength <= newLineOffset)) {
+      (contentNewLineOffset < 0 ||
+       mContentOffset + contentLength <= contentNewLineOffset)) {
     if (!cachedNewlineOffset) {
       cachedNewlineOffset = new NewlineProperty;
       if (cachedNewlineOffset) {
@@ -6779,7 +6790,7 @@ nsTextFrame::ReflowText(nsLineLayout& aLineLayout, nscoord aAvailableWidth,
     }
     if (cachedNewlineOffset) {
       cachedNewlineOffset->mStartOffset = offset;
-      cachedNewlineOffset->mNewlineOffset = newLineOffset;
+      cachedNewlineOffset->mNewlineOffset = contentNewLineOffset;
     }
   } else if (cachedNewlineOffset) {
     mContent->DeleteProperty(nsGkAtoms::newline);