Set vertical resize flags on the root's reflow state when we're doing SizeToContent reflows. (Bug 562955) r=bzbarsky a2.0=blocking2.0:betaN

layout/base/nsPresShell.cpp

@@ -1153,6 +1153,8 @@ protected:
 
   PRPackedBool mViewportOverridden;
 
+  PRPackedBool mLastRootReflowHadUnconstrainedHeight;
+
   // This is used to protect ourselves from triggering reflow while in the
   // middle of frame construction and the like... it really shouldn't be
   // needed, one hopes, but it is for now.
@@ -7716,6 +7718,23 @@ PresShell::DoReflow(nsIFrame* target, PRBool aInterruptible)
   nsSize reflowSize(size.width, NS_UNCONSTRAINEDSIZE);
   nsHTMLReflowState reflowState(mPresContext, target, rcx, reflowSize);
 
+  if (rootFrame == target) {
+    // When the root frame is being reflowed with unconstrained height
+    // (which happens when we're called from
+    // DocumentViewerImpl::SizeToContent), we're effectively doing a
+    // vertical resize, since it changes the meaning of percentage
+    // heights even if no heights actually changed.  The same applies
+    // when we reflow again after that computation.  This is an unusual
+    // case, and isn't caught by nsHTMLReflowState::InitResizeFlags.
+    PRBool hasUnconstrainedHeight = size.height == NS_UNCONSTRAINEDSIZE;
+
+    if (hasUnconstrainedHeight || mLastRootReflowHadUnconstrainedHeight) {
+      reflowState.mFlags.mVResize = PR_TRUE;
+    }
+
+    mLastRootReflowHadUnconstrainedHeight = hasUnconstrainedHeight;
+  }
+
   // fix the computed height
   NS_ASSERTION(reflowState.mComputedMargin == nsMargin(0, 0, 0, 0),
                "reflow state should not set margin for reflow roots");

layout/base/tests/Makefile.in

@@ -81,6 +81,7 @@ _TEST_FILES =	\
 		test_bug445810.html \
 		test_bug449781.html \
 		test_bug450930.xhtml \
+		test_bug458898.html \
 		test_bug465448.xul \
 		test_bug469170.html \
 		test_bug471126.html \
@@ -114,10 +115,8 @@ _TEST_FILES =	\
 		$(NULL)
 
 # Tests for bugs 441782, 467672 and 570378 don't pass reliably on Windows, because of bug 469208
-# Test for bug 458898 doesn't pass on Windows 7. See bug 562955.
 ifeq (,$(filter windows,$(MOZ_WIDGET_TOOLKIT)))
 _TEST_FILES += \
-		test_bug458898.html \
 		bidi_numeral_test.js \
 		test_bug332655-1.html \
 		test_bug332655-2.html \