Make flex-grow and flex-shrink interpolation continuous with 0

LayoutTests/transitions/flex-transitions.html

Index: LayoutTests/transitions/flex-transitions.html
diff --git a/LayoutTests/transitions/flex-transitions.html b/LayoutTests/transitions/flex-transitions.html
index a36efab5b5b3db2745abd34b0d4782269644a073..4d580a00c083327ebb931e8db406fcff23d3bd79 100644
--- a/LayoutTests/transitions/flex-transitions.html
+++ b/LayoutTests/transitions/flex-transitions.html
@@ -58,13 +58,13 @@
     const expectedValues = [
       // [time, element-id, property, expected-value, tolerance]
       [0.2, 'row1',      '-webkit-flex', [140, 0,     0], 10],
-      [0.2, 'column1',   '-webkit-flex', [0,   0,    40], 10], // grow/shrink do not transition to/from zero
+      [0.2, 'column1',   '-webkit-flex', [80,  0,    40], 10],
       [0.2, 'negative1', '-webkit-flex', [100, 100,  60], 10],
-      [0.2, 'no-flex1',  '-webkit-flex', [0,   0,     0], 10], // grow/shrink do not transition to/from zero
+      [0.2, 'no-flex1',  '-webkit-flex', [80,  0,     0], 10],
       [0.8, 'row1',      '-webkit-flex', [260, 0,     0], 10],
-      [0.8, 'column1',   '-webkit-flex', [0,   0,   160], 10], // grow/shrink do not transition to/from zero
+      [0.8, 'column1',   '-webkit-flex', [20,  0,   160], 10],
       [0.8, 'negative1', '-webkit-flex', [100, 100,  90], 10],
-      [0.8, 'no-flex1',  '-webkit-flex', [0,   0,     0], 10], // grow/shrink do not transition to/from zero
+      [0.8, 'no-flex1',  '-webkit-flex', [20,  0,     0], 10],
     ];
 
     function setupTest()