[llvm-cov] Remove some asserts in the html renderer (NFC)
[llvm-cov] Remove some asserts in the html renderer (NFC)

These asserts are making tests fragile. The renderer does not enter an
invalid state when they fail, however, it may spit out a garbled
coverage report because the source text no longer matches the provided
coverage mapping.

Another follow-up to r281072.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@281076 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm