Revert "Reland "[parser] Remove pretenuring of closures assigned to properties""

This reverts commit 3d7ad2e7.

Reason for revert: too many regressions to handle for now.

Original change's description:
> Reland "[parser] Remove pretenuring of closures assigned to properties"
>
> The memory gains were significant, so despite the bluebird-doxbee
> regression, we think it's better to have this patch than not.
> See the attached Chromium bug for more discussion.
>
> This is a reland of 20e346bd.
>
> Original change's description:
> > [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/914610
> > Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
> > Commit-Queue: Adam Klein <adamk@chromium.org>
> > Cr-Commit-Position: refs/heads/master@{#51254}
>
> Bug: v8:7442, chromium:814182
> Change-Id: I228c59dccef3844803f115749e72ae6c5f286eda
> Reviewed-on: https://chromium-review.googlesource.com/938241
> Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
> Commit-Queue: Adam Klein <adamk@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#51668}

Tbr: gsathya@chromium.org
Bug: v8:7442, v8:7524, chromium:814182, chromium:818627, chromium:818672, chromium:819994, chromium:821788
Change-Id: Ib760d63f879613f3b874889c5cb29ba2a77ba430
Reviewed-on: https://chromium-review.googlesource.com/980795
Commit-Queue: Adam Klein <adamk@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52233}

src/parsing/parser-base.h

@@ -3012,6 +3012,8 @@ 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

@@ -687,6 +687,16 @@ 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

@@ -1344,6 +1344,9 @@ 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