Store breakpoint positions in the WasmSharedModuleData in order to set
them on new instantiations. Also redirect them to all live instances at
the time the breakpoint is set.

Inside the WasmDebugInfo, we store the BreakPointInfo objects to find
hit breakpoints.

R=titzer@chromium.org, yangguo@chromium.org
BUG=v8:5822

Review-Url: https://codereview.chromium.org/2626253002
Cr-Commit-Position: refs/heads/master@{#42443}