fix: get source code from sourceMapStore on write report

Closes #72

Author: billowz

src/reporter.js

@@ -99,8 +99,10 @@ function CoverageIstanbulReporter(baseReporterDecorator, logger, config) {
  addCoverage(coverageMap, browserOrBrowsers);
  }
 
- const remappedCoverageMap = sourceMapStore.transformCoverage(coverageMap)
- .map;
+ const {
+ sourceFinder,
+ map: remappedCoverageMap
+ } = sourceMapStore.transformCoverage(coverageMap);
 
  if (!coverageConfig.skipFilesWithNoCoverage) {
  // On Windows, istanbul returns files with mixed forward/backslashes in them
@@ -117,7 +119,7 @@ function CoverageIstanbulReporter(baseReporterDecorator, logger, config) {
  }
 
  log.debug('Writing coverage reports:', reportTypes);
- reporter.write(remappedCoverageMap);
+ reporter.write(remappedCoverageMap, { sourceFinder });
 
  const userThresholds = coverageConfig.thresholds;