Backed out changeset 07def0eabf91 (bug 1308876)

layout/generic/crashtests/crashtests.list

@@ -500,7 +500,7 @@ load 784600.html
 load 785555.html
 load 786740-1.html
 load 790260-1.html
-test-pref(font.size.inflation.emPerLine,15) load 791601.xhtml
+asserts(1) test-pref(font.size.inflation.emPerLine,15) load 791601.xhtml # Bug 871327
 test-pref(font.size.inflation.minTwips,120) load 794693.html
 asserts-if(!Android,4) load 798020-1.html
 load 798235-1.html

layout/generic/nsBlockFrame.cpp

@@ -1996,6 +1996,9 @@ nsBlockFrame::PrepareResizeReflow(BlockReflowInput& aState)
     nscoord newAvailISize =
       aState.mReflowInput.ComputedLogicalBorderPadding().IStart(wm) +
       aState.mReflowInput.ComputedISize();
+    NS_ASSERTION(NS_UNCONSTRAINEDSIZE != aState.mReflowInput.ComputedLogicalBorderPadding().IStart(wm) &&
+                 NS_UNCONSTRAINEDSIZE != aState.mReflowInput.ComputedISize(),
+                 "math on NS_UNCONSTRAINEDSIZE");
 
 #ifdef DEBUG
     if (gNoisyReflow) {