Changes to show intellisense for @inject directive

[pranavkm]

Fixes aspnet/Razor#139

[yishaigalatzer]

Code change looks good, missing a test to make sure the right inject pattern in generated.

[NTaylorMullen]

1. Add a line mapping test for partially written @inject code, something like:
   https://github.com/aspnet/Razor/blob/dev/test/Microsoft.AspNet.Razor.Test/Generator/CSharpRazorCodeGeneratorTest.cs#L122-L134
2. Add a syntax tree test to validate that the correct inject syntax tree is generated for the partially written inject case (if we don't have one for the fully written case we should add that). Something like: https://github.com/aspnet/Razor/blob/dev/test/Microsoft.AspNet.Razor.Test/Parser/CSharp/CSharpDirectivesTest.cs#L16-L24 but for the partial case

[NTaylorMullen]

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