unsubscribe some subscriptions on destroy / first some subscriptions

src/lib/core/line/line.ts

@@ -25,7 +25,6 @@ export class MdLineSetter {
     });
   }
 
-
   private _setLineClass(count: number): void {
     this._resetClasses();
     if (count === 2 || count === 3) {

src/lib/dialog/dialog.ts

@@ -88,7 +88,7 @@ export class MdDialog {
     let dialogRef = <MdDialogRef<T>> new MdDialogRef(overlayRef);
 
     // When the dialog backdrop is clicked, we want to close it.
-    overlayRef.backdropClick().subscribe(() => dialogRef.close());
+    overlayRef.backdropClick().first().subscribe(() => dialogRef.close());
 
     // Set the dialogRef to the container so that it can use the ref to close the dialog.
     dialogContainer.dialogRef = dialogRef;

src/lib/icon/icon.ts

@@ -122,11 +122,11 @@ export class MdIcon implements OnChanges, OnInit, AfterViewChecked {
     if (changedInputs.indexOf('svgIcon') != -1 || changedInputs.indexOf('svgSrc') != -1) {
       if (this.svgIcon) {
         const [namespace, iconName] = this._splitIconName(this.svgIcon);
-        this._mdIconRegistry.getNamedSvgIcon(iconName, namespace).subscribe(
+        this._mdIconRegistry.getNamedSvgIcon(iconName, namespace).first().subscribe(
             svg => this._setSvgElement(svg),
             (err: any) => console.log(`Error retrieving icon: ${err}`));
       } else if (this.svgSrc) {
-        this._mdIconRegistry.getSvgIconFromUrl(this.svgSrc).subscribe(
+        this._mdIconRegistry.getSvgIconFromUrl(this.svgSrc).first().subscribe(
             svg => this._setSvgElement(svg),
             (err: any) => console.log(`Error retrieving icon: ${err}`));
       }

src/lib/sidenav/sidenav.ts

@@ -66,7 +66,6 @@ export class MdSidenav {
   /** Event emitted when the sidenav is fully closed. */
   @Output('close') onClose = new EventEmitter<void>();
 
-
   /**
    * @param _elementRef The DOM element reference. Used for transition and width calculation.
    *     If not available we do not hook on transitions.