Layout breaks when the first element has a different minWidth than the rest

Summary:
fixes react/yoga#2006

`distributeFreeSpaceFirstPass` decrements `totalFlexGrowFactors` /
`totalFlexShrinkScaledFactors` as it freezes items, but only reduces `remainingFreeSpace`
after the loop. Items after the first frozen one get an inflated fair share and freeze
spuriously. When the first item clamps, the whole line freezes and `remainingFreeSpace`
drains to 0, so the second pass has nothing to distribute and everything falls back to its
flex basis — a 540px row of three `flexGrow: 1` items with `maxWidth: 180` and minWidths
60/30/30 lays out as 60/30/30 instead of 180/180/180.

Snapshot both totals before the loop and divide by the snapshot. The first pass is then
iteration 1 of CSS Flexbox §9.7, and independent of child order.

Changelog:
[General][Fixed] - Fix a flex line collapsing to its minimum sizes when the first item clamps to its min or max main size

X-link: react/yoga#2021

Reviewed By: javache

Differential Revision: D119142409

Pulled By: pasqualeanatriello

Author: Dagur

packages/react-native/ReactCommon/yoga/yoga/algorithm/CalculateLayout.cpp

@@ -1280,6 +1280,19 @@ static void distributeFreeSpaceFirstPass(
   float boundMainSize = 0;
   float deltaFreeSpace = 0;
 
+  // The first pass performs a single distribution of the free space over all
+  // of the line's flexible items, so every item's tentative size must be
+  // computed against the *original* totals.  The totals are still reduced as
+  // items get frozen below (so the second pass can redistribute), but those
+  // reduced values must not feed back into the fair-share calculation for the
+  // remaining items: doing so inflates their tentative size and can freeze
+  // items that should still be able to grow/shrink (see
+  // https://github.com/react/yoga/issues/2006).
+  const float originalTotalFlexGrowFactors =
+      flexLine.layout.totalFlexGrowFactors;
+  const float originalTotalFlexShrinkScaledFactors =
+      flexLine.layout.totalFlexShrinkScaledFactors;
+
   for (auto currentLineChild : flexLine.itemsInFlow) {
     float childFlexBasis = boundAxisWithinMinAndMax(
                                currentLineChild,
@@ -1299,8 +1312,7 @@ static void distributeFreeSpaceFirstPass(
           flexShrinkScaledFactor != 0) {
         baseMainSize = childFlexBasis +
             flexLine.layout.remainingFreeSpace /
-                flexLine.layout.totalFlexShrinkScaledFactors *
-                flexShrinkScaledFactor;
+                originalTotalFlexShrinkScaledFactors * flexShrinkScaledFactor;
         boundMainSize = boundAxisWithAutoMin(
             currentLineChild,
             mainAxis,
@@ -1328,8 +1340,8 @@ static void distributeFreeSpaceFirstPass(
       // Is this child able to grow?
       if (yoga::isDefined(flexGrowFactor) && flexGrowFactor != 0) {
         baseMainSize = childFlexBasis +
-            flexLine.layout.remainingFreeSpace /
-                flexLine.layout.totalFlexGrowFactors * flexGrowFactor;
+            flexLine.layout.remainingFreeSpace / originalTotalFlexGrowFactors *
+                flexGrowFactor;
         boundMainSize = boundAxis(
             currentLineChild,
             mainAxis,