Bug 1489295 Part 1 - Rename frame construction data bit that creates flex/grid/column. r=dbaron

After supporting column-span, the top-level container for multicol
layout is no longer the ColumnSetFrame, so remove the "SET" suffix from
FCDATA_ALLOW_GRID_FLEX_COLUMNSET bit to make it sound more general.

Also, update the document and add an assertion.

Differential Revision: https://phabricator.services.mozilla.com/D24394

--HG--
extra : moz-landing-system : lando

layout/base/nsCSSFrameConstructor.cpp

@@ -3415,7 +3415,7 @@ nsCSSFrameConstructor::FindHTMLData(const Element& aElement,
       SIMPLE_TAG_CREATE(iframe, NS_NewSubDocumentFrame),
       {nsGkAtoms::button,
        FCDATA_WITH_WRAPPING_BLOCK(
-           FCDATA_ALLOW_BLOCK_STYLES | FCDATA_ALLOW_GRID_FLEX_COLUMNSET,
+           FCDATA_ALLOW_BLOCK_STYLES | FCDATA_ALLOW_GRID_FLEX_COLUMN,
            NS_NewHTMLButtonControlFrame, PseudoStyleType::buttonContent)},
       SIMPLE_TAG_CHAIN(canvas, nsCSSFrameConstructor::FindCanvasData),
       SIMPLE_TAG_CREATE(video, NS_NewHTMLVideoFrame),
@@ -3622,6 +3622,9 @@ void nsCSSFrameConstructor::ConstructFrameFromItemInternal(
   MOZ_ASSERT(
       !(bits & FCDATA_IS_WRAPPER_ANON_BOX) || (bits & FCDATA_USE_CHILD_ITEMS),
       "Wrapper anon boxes should always have FCDATA_USE_CHILD_ITEMS");
+  MOZ_ASSERT(!(bits & FCDATA_ALLOW_GRID_FLEX_COLUMN) ||
+                 (bits & FCDATA_CREATE_BLOCK_WRAPPER_FOR_ALL_KIDS),
+             "Need the block wrapper bit to create grid/flex/column.");
 
   // Don't create a subdocument frame for iframes if we're creating extra frames
   if (aState.mCreatingExtraFrames &&
@@ -3690,7 +3693,7 @@ void nsCSSFrameConstructor::ConstructFrameFromItemInternal(
       nsContainerFrame* container = static_cast<nsContainerFrame*>(newFrame);
       nsContainerFrame* outerFrame;
       nsContainerFrame* innerFrame;
-      if (bits & FCDATA_ALLOW_GRID_FLEX_COLUMNSET) {
+      if (bits & FCDATA_ALLOW_GRID_FLEX_COLUMN) {
         switch (display->mDisplay) {
           case StyleDisplay::Flex:
           case StyleDisplay::InlineFlex:

layout/base/nsCSSFrameConstructor.h

@@ -684,11 +684,12 @@ class nsCSSFrameConstructor final : public nsFrameManager {
      an SVG text frame. */
 #define FCDATA_IS_SVG_TEXT 0x80000
   /**
-   * When FCDATA_CREATE_BLOCK_WRAPPER_FOR_ALL_KIDS is set, this bit says
-   * if we should create a grid/flex/columnset container instead of
-   * a block wrapper when the styles says so.
+   * If FCDATA_ALLOW_GRID_FLEX_COLUMN is set, then we should create a
+   * grid/flex/column container instead of a block wrapper when the styles says
+   * so. This bit is meaningful only if FCDATA_CREATE_BLOCK_WRAPPER_FOR_ALL_KIDS
+   * is also set.
    */
-#define FCDATA_ALLOW_GRID_FLEX_COLUMNSET 0x200000
+#define FCDATA_ALLOW_GRID_FLEX_COLUMN 0x200000
   /**
    * Whether the kids of this FrameConstructionData should be flagged as having
    * a wrapper anon box parent.  This should only be set if