[CSS Grid Layout] Implement 'justify-items' parsing

Source/build/scripts/templates/StyleBuilderFunctions.cpp.tmpl

Index: Source/build/scripts/templates/StyleBuilderFunctions.cpp.tmpl
diff --git a/Source/build/scripts/templates/StyleBuilderFunctions.cpp.tmpl b/Source/build/scripts/templates/StyleBuilderFunctions.cpp.tmpl
index 25853f8c9e4e99feba4c022882a5823e29ecd179..d6ed9904d0e90aaded9a4f1fb6c912121132a533 100644
--- a/Source/build/scripts/templates/StyleBuilderFunctions.cpp.tmpl
+++ b/Source/build/scripts/templates/StyleBuilderFunctions.cpp.tmpl
@@ -514,8 +514,6 @@ namespace WebCore {
         state.style()->set{{alignment_type}}OverflowAlignment(*pairValue->second());
     } else {
         state.style()->set{{alignment_type}}(*primitiveValue);
-        // FIXME: We should clear the overflow-alignment mode here and probably
-        // also set it in the initial and inherit handlers
     }
 }
 {% endmacro %}
@@ -523,6 +521,25 @@ namespace WebCore {
 {{apply_alignment('CSSPropertyAlignItems', 'AlignItems')}}
 {{apply_alignment('CSSPropertyAlignSelf', 'AlignSelf')}}
 
+{% macro apply_alignment_with_legacy_keyword(property_id, alignment_type) %}
+{{declare_value_function(property_id)}}
+{
+    CSSPrimitiveValue* primitiveValue = toCSSPrimitiveValue(value);
+    if (Pair* pairValue = primitiveValue->getPairValue()) {
+        if (pairValue->first()->getValueID() == CSSValueLegacy) {
+            state.style()->set{{alignment_type}}IsLegacy(LegacyPositionTrue);
+            state.style()->set{{alignment_type}}(*pairValue->second());
+        } else {
+            state.style()->set{{alignment_type}}(*pairValue->first());
+            state.style()->set{{alignment_type}}OverflowAlignment(*pairValue->second());
+        }
+    } else {
+        state.style()->set{{alignment_type}}(*primitiveValue);
+    }
+}
+{% endmacro %}
+{{apply_alignment_with_legacy_keyword('CSSPropertyJustifyItems', 'JustifyItems')}}
+
 {% macro apply_svg_paint(property_id, paint_type) %}
 {% set property = properties[property_id] %}
 {{declare_initial_function(property_id)}}