Fix classpath generation for Eclipse project

The GWT libraries were not included in the classpath, resulting
in the project failing to build in Eclipse.

Explicitly add the libraries as dependencies.

Bug: Issue 8792
Change-Id: I56acf2edba29f9a72eb1c489c776dad12e28614f

tools/eclipse/BUILD

diff --git a/tools/eclipse/BUILD b/tools/eclipse/BUILD
index 2659b4d..abc0526 100644
--- a/tools/eclipse/BUILD
+++ b/tools/eclipse/BUILD
@@ -8,6 +8,8 @@
 classpath_collector(
     name = "main_classpath_collect",
     deps = PLUGIN_DEPS + GWT_PLUGIN_DEPS + [
+        "//external:gwt-dev",
+        "//external:gwt-user",
         "//:importer__plugin",
     ],
 )