Add missing download dependency to R8 with Java 11 task.

Change-Id: I426726b9e202a748e07f32dad895a3120c771978
diff --git a/build.gradle b/build.gradle
index 2edec91..f825010 100644
--- a/build.gradle
+++ b/build.gradle
@@ -566,6 +566,7 @@
 setJava11Compilation(sourceSets.jdk11TimeTests.compileJavaTaskName)
 
 task compileMainWithJava11 (type: JavaCompile) {
+    dependsOn downloadDeps
     def jdkDir = 'third_party/openjdk/jdk-11/'
     options.fork = true
     options.forkOptions.jvmArgs = []