Inline JsUtil helpers where applicable

Change-Id: I3a2e36299cb08e29303144084af593a8a52411cd
diff --git a/user/super/com/google/gwt/emul/java/lang/Double.java b/user/super/com/google/gwt/emul/java/lang/Double.java
index a30c839..422b34b 100644
--- a/user/super/com/google/gwt/emul/java/lang/Double.java
+++ b/user/super/com/google/gwt/emul/java/lang/Double.java
@@ -200,17 +200,15 @@
     return (int) d;
   }
 
-  public static boolean isFinite(double x) {
-    return JsUtils.isFinite(x);
-  }
+  @JsMethod(namespace = "<window>")
+  public static native boolean isFinite(double x);
 
   public static boolean isInfinite(double x) {
     return !isNaN(x) && !isFinite(x);
   }
 
-  public static boolean isNaN(double x) {
-    return JsUtils.isNaN(x);
-  }
+  @JsMethod(namespace = "<window>")
+  public static native boolean isNaN(double x);
 
   public static double longBitsToDouble(long bits) {
     long ihi = (long) (bits >> 32);
diff --git a/user/super/com/google/gwt/emul/javaemul/internal/JsUtils.java b/user/super/com/google/gwt/emul/javaemul/internal/JsUtils.java
index e569add..caed13e 100644
--- a/user/super/com/google/gwt/emul/javaemul/internal/JsUtils.java
+++ b/user/super/com/google/gwt/emul/javaemul/internal/JsUtils.java
@@ -18,7 +18,6 @@
 import javaemul.internal.annotations.DoNotAutobox;
 import javaemul.internal.annotations.UncheckedCast;
 import jsinterop.annotations.JsMethod;
-import jsinterop.annotations.JsProperty;
 
 /**
  * Provides an interface for simple JavaScript idioms that can not be expressed in Java.
@@ -29,24 +28,11 @@
   public static native double getTime();
 
   @JsMethod(namespace = "<window>")
-  public static native boolean isFinite(double d);
-
-  @JsMethod(namespace = "<window>")
-  public static native boolean isNaN(double d);
-
-  @JsMethod(namespace = "<window>")
   public static native int parseInt(String s, int radix);
 
-  @JsProperty(namespace = "<window>")
-  public static native Object getUndefined();
-
-  public static boolean isUndefined(Object value) {
-    return isSame(value, getUndefined());
-  }
-
-  public static native boolean isSame(Object x, Object y) /*-{
-    return x === y;
-   }-*/;
+  public static native boolean isUndefined(Object value) /*-{
+    return value === undefined;
+  }-*/;
 
   public static native double unsafeCastToDouble(Object number) /*-{
    return number;