Hyphenate html id attributes

html id attributes should not be valid JavaScript identifiers.

Change-Id: I482f2485dacd7401c5eb6e2a9fb6433b40a86056
diff --git a/java/com/google/gitiles/Renderer.java b/java/com/google/gitiles/Renderer.java
index 957e50d..65aea7e 100644
--- a/java/com/google/gitiles/Renderer.java
+++ b/java/com/google/gitiles/Renderer.java
@@ -52,7 +52,7 @@
  */
 public abstract class Renderer {
   // Must match .streamingPlaceholder.
-  private static final String PLACEHOLDER = "id=\"STREAMED_OUTPUT_BLOCK\"";
+  private static final String PLACEHOLDER = "id=\"STREAMED-OUTPUT-BLOCK\"";
 
   private static final ImmutableList<String> SOY_FILENAMES =
       ImmutableList.of(
diff --git a/resources/com/google/gitiles/templates/Common.soy b/resources/com/google/gitiles/templates/Common.soy
index c89f73c..c38f727 100644
--- a/resources/com/google/gitiles/templates/Common.soy
+++ b/resources/com/google/gitiles/templates/Common.soy
@@ -171,5 +171,5 @@
  * Renderer#renderStreaming(HttpServletResponse, String).
  */
 {template streamingPlaceholder}
-<br id="STREAMED_OUTPUT_BLOCK">
+<br id="STREAMED-OUTPUT-BLOCK">
 {/template}