Bug 1979643 - Modernize a for-loop in nsGridContainerFrame::Tracks::FindFrUnitSize r=dholbert

Differential Revision: https://phabricator.services.mozilla.com/D258879

Author: jfkthame

layout/generic/nsGridContainerFrame.cpp

@@ -7379,16 +7379,15 @@ float nsGridContainerFrame::Tracks::FindFrUnitSize(
 
     // 12.7.1.2: If flexFactorSum is less than 1, set it to 1 instead.
     hypotheticalFrSize = leftOverSpace / std::max(flexFactorSum, 1.0f);
-    for (uint32_t i = 0, len = flexTracks.Length(); i < len; ++i) {
-      uint32_t track = flexTracks[i];
+    for (uint32_t& track : flexTracks) {
       if (track == kAutoLine) {
         continue;  // Track marked as inflexible in a prev. iter of this loop.
       }
       float flexFactor = aFunctions.MaxSizingFor(track).AsFr();
       const nscoord base = mSizes[track].mBase;
       if (flexFactor * hypotheticalFrSize < base) {
         // 12.7.1.4: Treat this track as inflexible.
-        flexTracks[i] = kAutoLine;
+        track = kAutoLine;
         flexFactorSum -= flexFactor;
         leftOverSpace -= base;
         --numFlexTracks;