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 a8c16aa29366a7fc115e2c05033feeb9f069f5b1..89f6e452c25ad3b750e4b1e1f866e59ab0b29169 100644
--- a/tools/dom/docs/docs.json
+++ b/tools/dom/docs/docs.json
@@ -92,6 +92,18 @@
         ]
       }
     },
+    "Clipboard": {
+      "members": {
+        "getData": [
+          "/**",
+          "   * Gets the data for the specified MIME type.",
+          "   *",
+          "   * The  data is only available from within a drop operation (such as an",
+          "   * onDrop event) and will return `null` before then.",
+          "   */"
+        ]
+      }
+    },
     "Document": {
       "members": {
         "body": [