Revert of Set the javac target and source to 1.7 (patchset #2 id:20001 of...

Revert of Set the javac target and source to 1.7 (patchset #2 id:20001 of https://chromiumcodereview.appspot.com/545363002/)

Reason for revert:
Not all bots have Java 7 yet :(

Original issue's description:
> Set the javac target and source to 1.7
>
> BUG=336589
> TBR=yfriedman@chromium.org
>
> Committed: https://crrev.com/165c0f17fe5760a3f346940d4fb2574d62cfe53b
> Cr-Commit-Position: refs/heads/master@{#295162}

TBR=cjhopman@chromium.org,yfriedman@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=336589

Review URL: https://codereview.chromium.org/579543003

Cr-Commit-Position: refs/heads/master@{#295165}

base/android/java/src/org/chromium/base/CollectionUtil.java

@@ -17,14 +17,12 @@ import java.util.HashSet;
 public final class CollectionUtil {
     private CollectionUtil() {}
 
-    @SafeVarargs
     public static <E> HashSet<E> newHashSet(E... elements) {
         HashSet<E> set = new HashSet<E>(elements.length);
         Collections.addAll(set, elements);
         return set;
     }
 
-    @SafeVarargs
     public static <E> ArrayList<E> newArrayList(E... elements) {
         ArrayList<E> list = new ArrayList<E>(elements.length);
         Collections.addAll(list, elements);

build/android/gyp/javac.py

@@ -78,8 +78,8 @@ def DoJavac(
 
   javac_args = [
       '-g',
-      '-source', '1.7',
-      '-target', '1.7',
+      '-source', '1.5',
+      '-target', '1.5',
       '-classpath', ':'.join(classpath),
       '-d', classes_dir]
   if chromium_code: