Use the primitive "number" type instead of the object counterpart "Nu…

…mber" to avoid a jscompiler error.

An upcoming change to J2CL that simplifies how casting logic is transpiled will make the code "(Number) (Object) 3" here transpile to just "/** @type {Number} */ (3)" and jscompiler will see the "invalid cast" since "3" is not "Number" in the closure type system.

RELNOTES=n/a

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=225046969

guava-gwt/src-super/com/google/common/base/super/com/google/common/base/Platform.java

@@ -67,7 +67,7 @@ static native String emptyToNull(@Nullable String string) /*-{
     return string || null;
   }-*/;
 
-  @JsType(isNative = true, name = "Number", namespace = GLOBAL)
+  @JsType(isNative = true, name = "number", namespace = GLOBAL)
   private interface Number {
     double toPrecision(int precision);
   }