Add "name" property for classes as part of ClassDefinitionEvaluation

[anba]

SetFunctionName is currently called after ClassDefinitionEvaluation, which means the class name is not available in static class field initializers (tc39/proposal-class-fields#85) and may cause issues for a @frozen decorator (tc39/proposal-decorators#168).

This PR moves the initialization of the "name" property into ClassDefinitionEvaluation, which should avoid both aforementioned issues. I've split this PR into three parts for easier reviewing:

• The first commit 7bb51dd adds calls to a new runtime semantic NamedEvaluation to evaluate anonymous function definitions (as identified by IsAnonymousFunctionDefinition).

• 3d752d7 adds the actual definitions for NamedEvaluation.

• And the last commit 03fa5ba moves the "name" property assignment into ClassDefinitionEvaluation.

This PR doesn't result in any observable changes for non-class anonymous function definitions. For class definitions (with explicit and inferred names), the "name" property is now defined earlier, which is observable when calling [[OwnPropertyKeys]]. I don't expect to see any web-compatibility issues for this change given that all major engines already return the property keys of classes in a different order:

function printNames(kind, c) {
    c.foo = 0;
    print(`${kind}: ${Object.getOwnPropertyNames(c)}`);
}

// SM: prototype,m,foo,length,name
// JSC: length,name,prototype,m,foo
// V8: length,prototype,m,name,foo
// CH: prototype,length,name,m,foo
//
// Spec: length,prototype,m,name,foo
// Proposed: length,prototype,name,m,foo
printNames("class", class C { static m(){} });

// For comparison a normal function (Strict mode enabled to avoid non-standard arguments and caller.)
// SM: foo,prototype,length,name
// JSC: length,name,foo,prototype
// V8: length,name,prototype,foo
// CH: prototype,length,name,foo
//
// Spec: length,prototype,name,foo
printNames("function", function f(){ "use strict" });

[ljharb]

Grammar's not my strong suit, so I'll defer to others for that part of the review.

[littledan]

We got consensus on this change in the January 2019 TC39 meeting! Thanks everybody.

@anba Would you be interested in writing tests for this change?

[anba]

Created tc39/test262#2057