docs(bufferWhen): fix marble diagram (#6767)

docs_app/tools/marbles/diagrams/bufferWhen.txt

@@ -0,0 +1,15 @@
+[styles]
+event_radius = 33
+operator_height = 60
+completion_height = 80
+
+---a---b---c---d---e---f---g---h---|
+
+-------------s
+
+> bufferWhen()
+
+-------------x------------y--------(z|)
+x := [a, b, c]
+y := [d, e, f]
+z := [g, h]

spec/operators/bufferWhen-spec.ts

@@ -1,6 +1,6 @@
 import { expect } from 'chai';
-import { of, EMPTY, Observable } from 'rxjs';
-import { bufferWhen, mergeMap, takeWhile, take } from 'rxjs/operators';
+import { of } from 'rxjs';
+import { bufferWhen, mergeMap, takeWhile } from 'rxjs/operators';
 import { TestScheduler } from 'rxjs/testing';
 import { observableMatcher } from '../helpers/observableMatcher';
 
@@ -16,7 +16,7 @@ describe('bufferWhen operator', () => {
     testScheduler.run(({ hot, cold, expectObservable }) => {
       const e1 = hot('--a--^---b---c---d---e---f---g---------|   ');
       const e2 = cold('    --------------(s|)                    ');
-      //                                 --------------(s |)
+      //                                 --------------(s|)
       const expected = '   --------------x-------------y-----(z|)';
       const values = {
         x: ['b', 'c', 'd'],

src/internal/operators/bufferWhen.ts

@@ -13,7 +13,7 @@ import { innerFrom } from '../observable/innerFrom';
  * starts collecting values, it calls a function that returns an Observable that
  * tells when to close the buffer and restart collecting.</span>
  *
- * ![](bufferWhen.png)
+ * ![](bufferWhen.svg)
  *
  * Opens a buffer immediately, then closes the buffer when the observable
  * returned by calling `closingSelector` function emits a value. When it closes