--- a/layout/generic/ReflowInput.cpp
+++ b/layout/generic/ReflowInput.cpp
@@ -2394,19 +2394,20 @@ ReflowInput::InitConstraints(nsPresConte
         if (parentCBType == nsGkAtoms::gridContainerFrame) {
           alignCB = alignCB->GetParent();
           alignCBType = parentCBType;
         }
       }
       if (alignCBType == nsGkAtoms::gridContainerFrame) {
         // Shrink-wrap grid items that will be aligned (rather than stretched)
         // in its inline axis.
-        auto inlineAxisAlignment = wm.IsOrthogonalTo(cbwm) ?
-          mStylePosition->UsedAlignSelf(mFrame->StyleContext()->GetParent()) :
-          mStylePosition->UsedJustifySelf(mFrame->StyleContext()->GetParent());
+        auto inlineAxisAlignment =
+          wm.IsOrthogonalTo(cbwm)
+            ? mStylePosition->UsedAlignSelf(alignCB->StyleContext())
+            : mStylePosition->UsedJustifySelf(alignCB->StyleContext());
         if ((inlineAxisAlignment != NS_STYLE_ALIGN_STRETCH &&
              inlineAxisAlignment != NS_STYLE_ALIGN_NORMAL) ||
             mStyleMargin->mMargin.GetIStartUnit(wm) == eStyleUnit_Auto ||
             mStyleMargin->mMargin.GetIEndUnit(wm) == eStyleUnit_Auto) {
           computeSizeFlags =
             ComputeSizeFlags(computeSizeFlags | ComputeSizeFlags::eShrinkWrap);
         }
       } else {

--- a/layout/reftests/css-grid/grid-item-table-stretch-002-ref.html
+++ b/layout/reftests/css-grid/grid-item-table-stretch-002-ref.html
@@ -21,16 +21,17 @@
 
 table {
   border: 1px solid;
   padding: 0;
   margin: 0;
   background: lightgrey;
 }
 caption { border: 1px dashed blue; }
+caption { justify-self: stretch; } /* XXX: Workaround bug 1350037. */
 x { display:block; width:16px; height:16px; }
 t { display:block; width:6px; height:6px; }
 
 .w20 { width: 20px }
 .mxw2 { width: 2px }
 .mxw10 { width: 10px }
 .mw20 { width: 20px }
 .wfill { width:32px }

--- a/layout/style/nsComputedDOMStyle.cpp
+++ b/layout/style/nsComputedDOMStyle.cpp
@@ -4641,17 +4641,17 @@ nsComputedDOMStyle::DoGetJustifyContent(
 }
 
 already_AddRefed<CSSValue>
 nsComputedDOMStyle::DoGetJustifyItems()
 {
   RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
   nsAutoString str;
   auto justify =
-    StylePosition()->ComputedJustifyItems(mStyleContext->GetParent());
+    StylePosition()->ComputedJustifyItems(mStyleContext->GetParentAllowServo());
   nsCSSValue::AppendAlignJustifyValueToString(justify, str);
   val->SetString(str);
   return val.forget();
 }
 
 already_AddRefed<CSSValue>
 nsComputedDOMStyle::DoGetJustifySelf()
 {

--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -8664,17 +8664,17 @@ nsRuleNode::ComputePositionData(void* aS
            parentPos->mJustifyContent,
            NS_STYLE_JUSTIFY_NORMAL);
 
   // justify-items: enum, inherit, initial
   const auto& justifyItemsValue = *aRuleData->ValueForJustifyItems();
   if (MOZ_UNLIKELY(justifyItemsValue.GetUnit() == eCSSUnit_Inherit)) {
     if (MOZ_LIKELY(parentContext)) {
       pos->mJustifyItems =
-        parentPos->ComputedJustifyItems(parentContext->GetParent());
+        parentPos->ComputedJustifyItems(parentContext->GetParentAllowServo());
     } else {
       pos->mJustifyItems = NS_STYLE_JUSTIFY_NORMAL;
     }
     conditions.SetUncacheable();
   } else {
     SetValue(justifyItemsValue,
              pos->mJustifyItems, conditions,
              SETVAL_ENUMERATED | SETVAL_UNSET_INITIAL,

--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -1673,36 +1673,36 @@ nsStylePosition::UsedAlignSelf(nsStyleCo
 
 uint8_t
 nsStylePosition::ComputedJustifyItems(nsStyleContext* aParent) const
 {
   if (mJustifyItems != NS_STYLE_JUSTIFY_AUTO) {
     return mJustifyItems;
   }
   if (MOZ_LIKELY(aParent)) {
-    auto inheritedJustifyItems =
-      aParent->StylePosition()->ComputedJustifyItems(aParent->GetParent());
+    auto inheritedJustifyItems = aParent->StylePosition()->ComputedJustifyItems(
+      aParent->GetParentAllowServo());
     // "If the inherited value of justify-items includes the 'legacy' keyword,
     // 'auto' computes to the inherited value."  Otherwise, 'normal'.
     if (inheritedJustifyItems & NS_STYLE_JUSTIFY_LEGACY) {
       return inheritedJustifyItems;
     }
   }
   return NS_STYLE_JUSTIFY_NORMAL;
 }
 
 uint8_t
 nsStylePosition::UsedJustifySelf(nsStyleContext* aParent) const
 {
   if (mJustifySelf != NS_STYLE_JUSTIFY_AUTO) {
     return mJustifySelf;
   }
   if (MOZ_LIKELY(aParent)) {
-    auto inheritedJustifyItems = aParent->StylePosition()->
-      ComputedJustifyItems(aParent->GetParent());
+    auto inheritedJustifyItems = aParent->StylePosition()->ComputedJustifyItems(
+      aParent->GetParentAllowServo());
     return inheritedJustifyItems & ~NS_STYLE_JUSTIFY_LEGACY;
   }
   return NS_STYLE_JUSTIFY_NORMAL;
 }
 
 // --------------------
 // nsStyleTable
 //