Unflake inspector/profiler/heap-snapshot-summary-show-ranges.html

Call next() only once when testShowAll is complete.

Also added a check to InspectorTest.runHeapSnapshotTestSuite that completeProfilerTest is called only once.

BUG=None
R=alph@chromium.org, apavlov@chromium.org

Review URL: https://codereview.chromium.org/148463010

git-svn-id: svn://svn.chromium.org/blink/trunk@165931 bbb929c8-8fbe-4397-9dbb-9b2b20218538