Documenting misleading DataTransfer API.

tools/dom/docs/docs.json

Index: tools/dom/docs/docs.json
diff --git a/tools/dom/docs/docs.json b/tools/dom/docs/docs.json
index 09f9f5b0e5f66cde83c215ad3a098836485c76a4..4b67a7651ffeda653a487303c092d5b30bb58559 100644
--- a/tools/dom/docs/docs.json
+++ b/tools/dom/docs/docs.json
@@ -92,6 +92,28 @@
         ]
       }
     },
+    "Clipboard": {
+      "members": {
+        "getData": [
+          "/**",
+          "   * Gets the data for the specified type.",
+          "   *",
+          "   * The data is only available from within a drop operation (such as an",
+          "   * [Element.onDrop] event) and will return `null` before the event is",
+          "   * triggered.",
+          "   *",
+          "   * Data transfer is prohibited across domains. If a drag originates",
+          "   * from content from another domain or protocol (HTTP vs HTTPS) then the",
+          "   * data cannot be accessed.",
+          "   *",
+          "   * The [type] can have values such as:",
+          "   *",
+          "   * * `'Text'`",
+          "   * * `'URL'`",
+          "   */"
+        ]
+      }
+    },
     "Document": {
       "members": {
         "body": [