Have Runtime return values rather than throwing for the no-op GWT ver…

…sion.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=130810651

src/com/google/javascript/jscomp/gwt/super/java/lang/Runtime.java

@@ -19,14 +19,14 @@
 /** GWT compatible no-op replacement for {@code Runtime} */
 public class Runtime {
   public static Runtime getRuntime() {
-    throw new UnsupportedOperationException("Runtime.getRuntime not implemented");
+    return new Runtime();
   }
 
   public long totalMemory() {
-    throw new UnsupportedOperationException("Runtime.totalMemory not implemented");
+    return 0;
   }
 
   public long freeMemory() {
-    throw new UnsupportedOperationException("Runtime.freeMemory not implemented");
+    return 0;
   }
 }