[css-layout-api] Add very bad text around LineFragments

Author: bfgeek

css-layout-api/Overview.bs

@@ -311,6 +311,29 @@ interface Fragment {
 
     readonly attribute ChildBreakToken? breakToken;
 };
+
+/* NOTE EVERYTHING BELOW HERE IS SPECULATIVE */
+interface LineFragment : Fragment {
+    readonly attribute sequence<LineFragmentSegment> segments;
+};
+
+interface LineFragmentSegment {
+    readonly attribute LineFragmentSegmentType type;
+    readonly attribute LineFragmentSegmentBreakType breakType;
+    readonly attribute FontMetrics? metrics;
+    readonly attribute double inlineOffset;
+};
+
+enum LineFragmentSegmentType {
+    "word-break",
+    "atomic-inline",
+    /* TODO add others here, not sure yet. */
+};
+
+enum LineFragmentSegmentBreakType {
+    "something"
+    /* TODO add others here, not sure yet. */
+};
 </pre>
 
 A {{Fragment}} represents a CSS <a>fragment</a> of a {{LayoutChild}} after layout has occurred on