[parser] Remove pretenuring of closures assigned to properties

This pretenuring was added in https://codereview.chromium.org/5220007,
back when it was necessary in order to allow use of the closure
as a "constant function" property. This should no longer be the case,
and the pretenuring causes some unfortunate downstream effects.

This patch removes the parser's setting of this bit. If it doesn't
cause regressions on the perf bots, followup CLs will remove the
rest of the support for this feature.

Bug: v8:7442
Change-Id: I27c43dd4293ce5de921be6c78571e712778d138a
Reviewed-on: https://chromium-review.googlesource.com/914610Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51254}

src/parsing/parser-base.h

@@ -2982,8 +2982,6 @@ ParserBase<Impl>::ParseAssignmentExpression(bool accept_IN, bool* ok) {
     function_state_->AddProperty();
   }
 
-  impl()->CheckAssigningFunctionLiteralToProperty(expression, right);
-
   if (fni_ != nullptr) {
     // Check if the right hand side is a call to avoid inferring a
     // name if we're dealing with "a = function(){...}();"-like

src/parsing/parser.h

@@ -742,16 +742,6 @@ class V8_EXPORT_PRIVATE Parser : public NON_EXPORTED_BASE(ParserBase<Parser>) {
     fni_->Infer();
   }
 
-  // If we assign a function literal to a property we pretenure the
-  // literal so it can be added as a constant function property.
-  V8_INLINE static void CheckAssigningFunctionLiteralToProperty(
-      Expression* left, Expression* right) {
-    DCHECK_NOT_NULL(left);
-    if (left->IsProperty() && right->IsFunctionLiteral()) {
-      right->AsFunctionLiteral()->set_pretenure();
-    }
-  }
-
   // Determine if the expression is a variable proxy and mark it as being used
   // in an assignment or with a increment/decrement operator.
   V8_INLINE static void MarkExpressionAsAssigned(Expression* expression) {

src/parsing/preparser.h

@@ -1298,9 +1298,6 @@ class PreParser : public ParserBase<PreParser> {
       const PreParserExpression& expression) {}
   V8_INLINE static void InferFunctionName() {}
 
-  V8_INLINE static void CheckAssigningFunctionLiteralToProperty(
-      const PreParserExpression& left, const PreParserExpression& right) {}
-
   V8_INLINE void MarkExpressionAsAssigned(
       const PreParserExpression& expression) {
     // TODO(marja): To be able to produce the same errors, the preparser needs