[DevTools] Move 'this' evaluation from ExecutionContext to autocomplete.

third_party/WebKit/Source/devtools/front_end/object_ui/JavaScriptAutocomplete.js

Index: third_party/WebKit/Source/devtools/front_end/object_ui/JavaScriptAutocomplete.js
diff --git a/third_party/WebKit/Source/devtools/front_end/object_ui/JavaScriptAutocomplete.js b/third_party/WebKit/Source/devtools/front_end/object_ui/JavaScriptAutocomplete.js
index 78d6dcc73dcc71ced31bc1b9ffe4920fdf94d50b..9fa7447540dd36ef47317da258b5997304afa468 100644
--- a/third_party/WebKit/Source/devtools/front_end/object_ui/JavaScriptAutocomplete.js
+++ b/third_party/WebKit/Source/devtools/front_end/object_ui/JavaScriptAutocomplete.js
@@ -70,7 +70,7 @@ ObjectUI.JavaScriptAutocomplete._mapCompletions = function(text, query) {
   var clippedExpression = ObjectUI.JavaScriptAutocomplete._clipExpression(text.substring(0, mapMatch.index));
   var fulfill;
   var promise = new Promise(x => fulfill = x);
-  executionContext.evaluate(clippedExpression, 'completion', true, true, false, false, false, evaluated);
+  executionContext.evaluate(clippedExpression || 'this', 'completion', true, true, false, false, false, evaluated);
   return promise;
 
   /**
@@ -190,7 +190,7 @@ ObjectUI.JavaScriptAutocomplete.completionsForExpression = function(expressionSt
   if (!expressionString && selectedFrame)
     variableNamesInScopes(selectedFrame, receivedPropertyNames);
   else
-    executionContext.evaluate(expressionString, 'completion', true, true, false, false, false, evaluated);
+    executionContext.evaluate(expressionString || 'this', 'completion', true, true, false, false, false, evaluated);
 
   return promise;
   /**