Pending breakpoints aren't resolved at startup unless their scripts have sourcemaps

[roblourens]

In a webserver or webpack/meteor-type scenario, when we can't anticipate the scripts path in the runtime, needed to make breakpoints bind at startup. Workaround - set the breakpoints after the script is loaded instead of before.

[roblourens]

const sourceMapsP = this._sourceMapTransformer.scriptParsed(mappedUrl, script.sourceMapURL).then(sources => {
            if (sources) {
                sources.forEach(source => {
                    if (this._pendingBreakpointsByUrl.has(source)) {
                        this.resolvePendingBreakpoint(this._pendingBreakpointsByUrl.get(source))
                            .then(() => this._pendingBreakpointsByUrl.delete(source));
                    }
                });
            }
        });