Deoptimize context value in Turbofan (and Crankshaft).

test/mjsunit/regress/regress-crbug-171715.js

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 // Flags: --expose-debug-as debug
+// Flags: --turbo-deoptimization
 
 Debug = debug.Debug
 
 var error = null;
 var test = 0;
 
 function check_v(expected, exec_state, frame_id) {
   assertEquals(expected, exec_state.frame(frame_id).evaluate('v').value());
 }
 
@@ skipping 39 matching lines @@
 })("a", "b", "c");
 assertNull(error);
 
 (function() {  // Test 3
   var v = 'inner0';  // Local eval overwrites this value.
   eval("var v = 'inner1'; " +
        "(function() { var v = 'inner2'; debugger; })('x', 'y', 'z');");
   assertEquals('inner1', v);  // Overwritten by local eval.
 })("a", "b", "c");
 assertNull(error);