This test runs a simple looped computation to test focusing and
    exclusion functionality of profile view grid.
    
    
    To use this test:
    
      - load file in the browser;
      
- open DevTools (Ctrl+Shift+I on Win/Linux, Command+Option+I on Mac);
      
- go to 'Profiles' page;
      
- press 'Start profiling' button
        (gray dot on the left side of status bar);
      
- wait for 5 seconds;
      
- press 'Stop profiling' button
        (red dot on the left side of status bar);
    
    On the left pane under 'CPU profiles' section, an item called
    'Profile 1' must appear, and a grid with profile data must
    appear on the right. Now test the following functionality in the grid:
    
    TEST 1:
    
      - select 'eternal_fib' function entry (without expanding it),
        press 'Focus
        on selected function' button (eye on the right of the status bar);
      
- ensure that only 'eternal_fib' function and its children are 
        left in the tree, and 'Total' column for the function shows
        '100%' value;
      
- expand 'eternal_fib' function node;
      
- press 'Restore all functions' button;
      
- verify that the value in 'Total' column is less than 100%;
      
- verify that 'eternal_fib' function node is can still be
        collapsed and expanded back;
    
    TEST 2:
    
      - expand two levels of 'Script:' node, select the second-level
        node;
      
- repeat the same steps for the selected node (in this case, immediate
        parent nodes of the focused node must also remain visible after
        focusing);
    
    TEST 3:
    
      - by expanding 'Script:' node, make sure that at least 3
        'eternal_fib' function nodes are visible;
      
- select any of 'eternal_fib' nodes and press
        'Exclude selected function' (cross) button on the status bar;
      
- verify that all 'eternal_fib' nodes are no more visible;
      
- expand more 'Script:' node levels, verify that no new
        'eternal_fib' nodes appear with expansion;
      
- press 'Restore all functions' button;
      
- verify that 'eternal_fib' nodes are now visible;
    
    TESTS 4 and 5:
    
    Now switch to 'Tree (Top Down)' view and repeat testing steps.
    For the 'Exclude selected function' function test, use 
    'Script:' function node, as 'eternal_fib' has only
    one entry in this view.