fix(compiler-cli): Pass SourceFile to getLeadingTriviaWidth

[kyliau]

This commit fixes a crash in the Angular Kythe indexer caused by failure
to retrieve SourceFile in a Statement.

Crash logs:

  TypeError: Cannot read property 'text' of undefined
    at Object.getTokenPosOfNode (typescript/stable/lib/typescript.js:8957:72)
    at NodeObject.getStart (typescript/stable/lib/typescript.js:121419:23)
    at NodeObject.getLeadingTriviaWidth (typescript/stable/lib/typescript.js:121439:25)
    at FactoryGenerator.generate (angular2/rc/packages/compiler-cli/src/ngtsc/shims/src/factory_generator.ts:64:49)
    at GeneratedShimsHostWrapper.getSourceFile (angular2/rc/packages/compiler-cli/src/ngtsc/shims/src/host.ts:88:26)
    at findSourceFile (typescript/stable/lib/typescript.js:90654:29)
    at typescript/stable/lib/typescript.js:90553:85
    at getSourceFileFromReferenceWorker (typescript/stable/lib/typescript.js:90520:34)
    at processSourceFile (typescript/stable/lib/typescript.js:90553:13)
    at processRootFile (typescript/stable/lib/typescript.js:90383:13)

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• angular.io application / infrastructure changes
• Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

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