fix(sidenav): remove min-width (#7748)

* fix(sidenav): remove min-width

* fixed tests

Author: mmalerba

src/lib/sidenav/drawer.scss

@@ -106,7 +106,6 @@ $mat-drawer-over-drawer-z-index: 4;
   top: 0;
   bottom: 0;
   z-index: 3;
-  min-width: 5vw;
   outline: 0;
   box-sizing: border-box;
   overflow-y: auto; // TODO(kara): revisit scrolling behavior for drawers

src/lib/sidenav/drawer.spec.ts

@@ -665,7 +665,7 @@ class DrawerDelayed {
 @Component({
   template: `
     <mat-drawer-container>
-      <mat-drawer *ngIf="renderDrawer" [mode]="mode"></mat-drawer>
+      <mat-drawer *ngIf="renderDrawer" [mode]="mode" style="width:100px"></mat-drawer>
     </mat-drawer-container>`,
 })
 class DrawerContainerStateChangesTestApp {