Change Constructor extAttr to constructor() op (#141)

* Change Constructor extAttr to constructor() op

fixes #139

* Fix nit

Author: Marcos Cáceres

index.bs

@@ -220,10 +220,10 @@ if any such underlying storage exists.
 Further normative definition of <a>snapshot state</a> can be found for {{File}}s.
 
 <xmp class="idl">
-[Constructor(optional sequence<BlobPart> blobParts,
-             optional BlobPropertyBag options = {}),
- Exposed=(Window,Worker), Serializable]
+[Exposed=(Window,Worker), Serializable]
 interface Blob {
+  constructor(optional sequence<BlobPart> blobParts,
+              optional BlobPropertyBag options = {});
 
   readonly attribute unsigned long long size;
   readonly attribute DOMString type;
@@ -643,11 +643,11 @@ and must follow the <dfn export>file type guidelines</dfn> below:
   including statistical methods.
 
 <pre class="idl">
-[Constructor(sequence&lt;BlobPart> fileBits,
-             USVString fileName,
-             optional FilePropertyBag options = {}),
- Exposed=(Window,Worker), Serializable]
+[Exposed=(Window,Worker), Serializable]
 interface File : Blob {
+  constructor(sequence&lt;BlobPart> fileBits,
+              USVString fileName,
+              optional FilePropertyBag options = {});
   readonly attribute DOMString name;
   readonly attribute long long lastModified;
 };
@@ -895,9 +895,9 @@ It is to be used for features that trigger in response to asynchronously reading
 ## The {{FileReader}} API ## {#APIASynch}
 
 <pre class="idl">
-[Constructor, Exposed=(Window,Worker)]
+[Exposed=(Window,Worker)]
 interface FileReader: EventTarget {
-
+  constructor();
   // async read methods
   void readAsArrayBuffer(Blob blob);
   void readAsBinaryString(Blob blob);
@@ -1289,8 +1289,9 @@ This interface  provides methods to <dfn id="read-method-sync" lt="synchronous r
 {{File}} or {{Blob}} objects into memory.
 
 <pre class="idl">
-[Constructor, Exposed=(DedicatedWorker,SharedWorker)]
+[Exposed=(DedicatedWorker,SharedWorker)]
 interface FileReaderSync {
+  constructor();
   // Synchronously return strings
 
   ArrayBuffer readAsArrayBuffer(Blob blob);