Bug 997590 (part 1) - Remove a dead else-branch. r=sstangl.

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extra : rebase_source : e126b0c5189f7845b7d6c1fc1a65aaca4d7dab12
Bug 997590 (part 2) - Create RegExpStaticsObjects lazily. r=sstangl.

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extra : rebase_source : 9cffd8ad8d3e66bb523cb1c127ca066847e34ee6